U.S. patent application number 17/149005 was filed with the patent office on 2022-03-24 for toner for developing electrostatic charge image, electrostatic charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method.
This patent application is currently assigned to FUJI XEROX CO., LTD.. The applicant listed for this patent is FUJI XEROX CO., LTD.. Invention is credited to Shintaro ANNO, Yoshimasa FUJIHARA, Satoshi MIURA, Daisuke NOGUCHI, Atsushi SUGAWARA.
Application Number | 20220091529 17/149005 |
Document ID | / |
Family ID | 1000005383795 |
Filed Date | 2022-03-24 |
United States Patent
Application |
20220091529 |
Kind Code |
A1 |
ANNO; Shintaro ; et
al. |
March 24, 2022 |
TONER FOR DEVELOPING ELECTROSTATIC CHARGE IMAGE, ELECTROSTATIC
CHARGE IMAGE DEVELOPER, TONER CARTRIDGE, PROCESS CARTRIDGE, IMAGE
FORMING APPARATUS, AND IMAGE FORMING METHOD
Abstract
A toner for developing an electrostatic charge image contains
toner particles containing at least one binder resin; the Mg
element in an amount such that the net intensity of x-ray
fluorescence from the Mg element in the toner is 0.10 kcps or more
and 1.20 kcps or less; and external additives including particles
of at least one compound represented by formula (1) and particles
of a metal salt of a fatty acid, MTiO.sub.3 (1) where M represents
at least one selected from the group consisting of Ca, Sr, and
Ba.
Inventors: |
ANNO; Shintaro; (Kanagawa,
JP) ; FUJIHARA; Yoshimasa; (Kanagawa, JP) ;
SUGAWARA; Atsushi; (Kanagawa, JP) ; NOGUCHI;
Daisuke; (Kanagawa, JP) ; MIURA; Satoshi;
(Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI XEROX CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
FUJI XEROX CO., LTD.
Tokyo
JP
|
Family ID: |
1000005383795 |
Appl. No.: |
17/149005 |
Filed: |
January 14, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G 9/08755 20130101;
G03G 9/0819 20130101; G03G 9/09733 20130101; G03G 15/0865 20130101;
G03G 21/1814 20130101; G03G 9/09791 20130101; G03G 9/09708
20130101 |
International
Class: |
G03G 9/097 20060101
G03G009/097; G03G 9/087 20060101 G03G009/087; G03G 9/08 20060101
G03G009/08; G03G 15/08 20060101 G03G015/08; G03G 21/18 20060101
G03G021/18 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2020 |
JP |
2020-159125 |
Claims
1. A toner for developing an electrostatic charge image, the toner
comprising: toner particles containing at least one binder resin; a
Mg element in an amount such that a net intensity of x-ray
fluorescence from the Mg element in the toner is 0.10 kcps or more
and 1.20 kcps or less; and external additives including particles
of at least one compound represented by formula (1) below and
particles of a metal salt of a fatty acid, MTiO.sub.3 (1) where M
represents at least one selected from the group consisting of Ca,
Sr, and Ba.
2. The toner according to claim 1 for developing an electrostatic
charge image, wherein the particles of at least one compound
represented by formula (1) have an average primary-particle
diameter of 30 nm or more and 3000 nm or less.
3. The toner according to claim 2 for developing an electrostatic
charge image, wherein the particles of at least one compound
represented by formula (1) have an average primary-particle
diameter of 70 nm or more and 130 nm or less.
4. The toner according to claim 1 for developing an electrostatic
charge image, wherein a ratio D/d1 between a volume-average
diameter D of the toner particles and an average primary-particle
diameter d1 of the particles of at least one compound represented
by formula (1) is 1.9 or more and 200 or less.
5. The toner according to claim 2 for developing an electrostatic
charge image, wherein a ratio D/d1 between a volume-average
diameter D of the toner particles and an average primary-particle
diameter d1 of the particles of at least one compound represented
by formula (1) is 1.9 or more and 200 or less.
6. The toner according to claim 4 for developing an electrostatic
charge image, wherein the ratio D/d1 between a volume-average
diameter D of the toner particles and an average primary-particle
diameter d1 of the particles of at least one compound represented
by formula (1) is 10 or more and 100 or less.
7. The toner according to claim 1 for developing an electrostatic
charge image, wherein the particles of a metal salt of a fatty acid
are particles of a zinc salt of a fatty acid.
8. The toner according to claim 7 for developing an electrostatic
charge image, wherein the particles of a metal salt of a fatty acid
are particles of zinc stearate.
9. The toner according to claim 1 for developing an electrostatic
charge image, wherein the binder resin includes an amorphous resin
and at least one crystalline resin.
10. The toner according to claim 9 for developing an electrostatic
charge image, wherein the crystalline resin includes at least one
polycondensate of a linear aliphatic .alpha.,.omega.-dicarboxylic
acid and a linear aliphatic .alpha.,.omega.-diol.
11. The toner according to claim 10 for developing an electrostatic
charge image, wherein the polycondensate of a linear aliphatic
.alpha.,.omega.-dicarboxylic acid and a linear aliphatic
.alpha.,.omega.-diol includes a polycondensate of
1,10-decanedicarboxylic acid and 1,6-hexanediol.
12. The toner according to claim 1 for developing an electrostatic
charge image, wherein: the toner particles further contain at least
one release agent; and the release agent includes an ester wax.
13. The toner according to claim 12 for developing an electrostatic
charge image, wherein the release agent includes an ester wax
formed by a C10 to C30 higher fatty acid and a monohydric or
polyhydric C1 to C30 alcohol component.
14. The toner according to claim 9 for developing an electrostatic
charge image, wherein in a cross-sectional observation of the toner
particles, there are toner particles in which at least two domains
of the crystalline resin meet conditions (A), (B1), (C), and (D)
below: condition (A) that each domain of the crystalline resin has
an aspect ratio of 5 or more and 40 or less; condition (B1) that
each domain of the crystalline resin measures 0.5 .mu.m or more and
1.5 .mu.m or less along a major axis thereof; condition (C) that a
line extended from the major axis of each domain of the crystalline
resin makes an angle of 60.degree. or more and 90.degree. or less
with a tangent to a surface of the toner particle at a point of
contact between the extended line and the surface; and condition
(D) that lines extended from the major axis of the two domains of
the crystalline resin cross each other at an angle of 45.degree. or
more and 90.degree. or less.
15. The toner according to claim 9 for developing an electrostatic
charge image, wherein in a cross-sectional observation of the toner
particles, there are toner particles in which at least two domains
of the crystalline resin meet conditions (A), (B2), (C), and (D)
below: condition (A) that each domain of the crystalline resin has
an aspect ratio of 5 or more and 40 or less; condition (B2) that at
least one of the two domains of the crystalline resin measures that
along a major axis thereof that 10% or more and 30% or less of a
longest diameter of the toner particle; condition (C) that a line
extended from the major axis of each domain of the crystalline
resin makes an angle of 60.degree. or more and 90.degree. or less
with a tangent to a surface of the toner particle at a point of
contact between the extended line and the surface; and condition
(D) that lines extended from the major axis of the two domains of
the crystalline resin cross each other at an angle of 45.degree. or
more and 90.degree. or less.
16. An electrostatic charge image developer comprising the toner
according to claim 1 for developing an electrostatic charge
image.
17. A toner cartridge that is attached to and detached from an
image forming apparatus, the toner cartridge comprising the toner
according to claim 1 for developing an electrostatic charge
image.
18. A process cartridge that is attached to and detached from an
image forming apparatus, the process cartridge comprising a
developing component that contains the electrostatic charge image
developer according to claim 16 and develops, using the
electrostatic charge image developer, an electrostatic charge image
on a surface of an image carrier to form a toner image.
19. An image forming apparatus comprising: an image carrier; a
charging component that charges a surface of the image carrier; an
electrostatic charge image creating component that creates an
electrostatic charge image on the charged surface of the image
carrier; a developing component that contains the electrostatic
charge image developer according to claim 16 and develops, using
the electrostatic charge image developer, the electrostatic charge
image on the surface of the image carrier to form a toner image; a
transfer component that transfers the toner image on the surface of
the image carrier to a surface of a recording medium; and a fixing
component that fixes the toner image on the surface of the
recording medium.
20. An image forming method comprising: charging a surface of an
image carrier; creating an electrostatic charge image on the
charged surface of the image carrier; developing, using the
electrostatic charge image developer according to claim 16, the
electrostatic charge image on the surface of the image carrier to
form a toner image; transferring the toner image on the surface of
the image carrier to a surface of a recording medium; and fixing
the toner image on the surface of the recording medium.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2020-159125 filed Sep.
23, 2020.
BACKGROUND
(i) Technical Field
[0002] The present disclosure relates to a toner for developing an
electrostatic charge image, an electrostatic charge image
developer, a toner cartridge, a process cartridge, an image forming
apparatus, and an image forming method.
(ii) Related Art
[0003] Electrophotography and other techniques for visualizing
image information are used in various fields today. In
electrophotographic visualization of image information, the surface
of an image carrier is charged, and an electrostatic charge image,
which is the image information, is created thereon. Then a
developer, which contains toner, is applied to form a toner image
on the surface of the image carrier.
[0004] This toner image is transferred to a recording medium and
fixed on the recording medium.
[0005] Japanese Unexamined Patent Application Publication No.
11-237766, for example, discloses a color toner that contains (i)
color toner particles containing at least a binder resin and a
colorant and (ii) external additives. The color toner is
characterized in that (a) the particles of the color toner have a
weight-average diameter of 5 to 8 .mu.m and a number-average
diameter of 4.5 to 7.5 .mu.m, the percentage of particles having a
diameter of 4 .mu.m or less in the color toner is between 5% and
40% by number, and the percentage of particles having a diameter of
10.08 .mu.m or more in the color toner is 7% by volume or less; (b)
the external additives include an inorganic powder selected from
the group consisting of a powder of strontium titanate, a powder of
cerium oxide, and a powder of calcium titanate and also include a
fine powder of hydrophobic alumina, the particles of the inorganic
powder have a length-average diameter of 0.2 to 2 .mu.m, and the
particles of the fine powder of hydrophobic alumina have a
length-average diameter of 0.005 to 0.1 .mu.m; (c) the binder resin
is a polyester resin crosslinked by a crosslinker; (d) each gram of
the color toner particles contains 0 to 20 mg of
chloroform-insoluble components; and (e) the color toner has a
storage modulus at a temperature of 130.degree. C. (G'.sub.130) of
2.times.10.sup.3 to 2.times.10.sup.4 [dyn/cm.sup.2] and a storage
modulus at a temperature of 170.degree. C. (G'.sub.170) of
5.times.10.sup.3 to 5.times.10.sup.4 [dyn/cm.sup.2], and
G'.sub.170/G'.sub.130 is between 0.25 and 10.
[0006] Japanese Unexamined Patent Application Publication No.
2019-120846 discloses a toner for developing an electrostatic
charge image that contains base particles and an external additive
on the surface thereof. The external additive contains particles of
calcium titanate having an average primary-particle diameter of 50
to 150 nm and particles of alumina, and the particles of alumina
have an average primary-particle diameter equal to or smaller than
that of the particles of calcium titanate.
SUMMARY
[0007] Aspects of non-limiting embodiments of the present
disclosure relate to a toner for developing an electrostatic charge
image that contains toner particles containing a binder resin and
also contains external additives. With this toner, images may have
fewer voids than with toners that contain Mg in an amount such that
in an x-ray fluorescence analysis of the toner, the net intensity
of the peak for Mg is less than 0.10 kcps or more than 1.20 kcps or
with toners in which particles of silica are the only external
additive.
[0008] Aspects of certain non-limiting embodiments of the present
disclosure overcome the above disadvantages and/or other
disadvantages not described above. However, aspects of the
non-limiting embodiments are not required to overcome the
disadvantages described above, and aspects of the non-limiting
embodiments of the present disclosure may not overcome any of the
disadvantages described above.
[0009] According to an aspect of the present disclosure, there is
provided a toner for developing an electrostatic charge image. The
toner contains toner particles containing at least one binder
resin; a Mg element in an amount such that a net intensity of x-ray
fluorescence from the Mg element in the toner is 0.10 kcps or more
and 1.20 kcps or less; and external additives including particles
of at least one compound represented by formula (1) below and
particles of a metal salt of a fatty acid,
MTiO.sub.3 (1)
where M represents at least one selected from the group consisting
of Ca, Sr, and Ba.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Exemplary embodiments of the present disclosure will be
described in detail based on the following figures, wherein:
[0011] FIG. 1 is a schematic view of the structure of an example of
an image forming apparatus according to an exemplary
embodiment;
[0012] FIG. 2 is a schematic view of the structure of an example of
a process cartridge according to an exemplary embodiment; and
[0013] FIG. 3 is a schematic view of a cross-section of a toner
particle in a toner according to an exemplary embodiment for
developing an electrostatic charge image.
DETAILED DESCRIPTION
[0014] The following describes exemplary embodiments of the present
disclosure in detail.
[0015] The following description includes series of numerical
ranges. In such a series, the upper or lower limit of a numerical
range may be substituted with that of another in the same
series.
[0016] The upper or lower limit of a numerical range, furthermore,
may be substituted with a value indicated in the Examples
section.
[0017] An ingredient of a composition described herein may be a
combination of multiple substances. In that case, the amount of the
ingredient in the composition is the total amount of the multiple
substances in the composition unless stated otherwise.
[0018] A gerund or action noun used in relation to a certain
process or method herein does not always represent an independent
action. As long as its purpose is fulfilled, the action represented
by the gerund or action noun may be continuous with or part of
another. Toner for Developing an Electrostatic Charge Image
[0019] A toner according to an exemplary embodiment for developing
an electrostatic charge image contains toner particles containing
at least one binder resin; the Mg element in an amount such that
the net intensity of x-ray fluorescence from the Mg element in the
toner is 0.10 kcps or more and 1.20 kcps or less; and external
additives including particles of at least one compound represented
by formula (1) and particles of a metal salt of a fatty acid,
MTiO.sub.3 (1)
where M represents at least one selected from the group consisting
of Ca, Sr, and Ba.
[0020] Particles of a compound represented by formula (1)
(hereinafter also referred to simply as "particles of formula (1)")
are highly hygroscopic. If a toner containing them is used with an
image forming apparatus under humid conditions, therefore, the
particles become sticky and affect the flow of the toner and
external additives at the area of contact between the cleaning
blade and the image carrier (blade nip), where the toner and
external additives accumulate. The reduced flow causes an increased
strain on the blade, causing the blade to polish the image carrier
too strongly. As a result, the blade nip wears unevenly between its
portion through which no recording medium passes and its image
portion because of different amounts of toner supply. The inventors
found that this uneven wear escalates especially after a high-load
"stress" run, during which the external additives sink deep in the
toner and affect the flow there seriously. Once this occurs, images
may often have voids because the particles of formula (1) are
easily concentrated in the worn portion.
[0021] If toner particles contain the Mg element, adsorbed water
adheres preferentially to the Mg compound present near the surface
of the toner particles. If such toner particles further contain
particles of formula (1) and particles of a metal salt of a fatty
acid (hereinafter also referred to as "metal salt particles") as
external additives, these particles bind with the water adsorbed by
the toner particles. At the blade nip, the metal salt particles
form loose aggregates around the toner particles and particles of
formula (1) as cores. The loose aggregates of the metal salt
particles are formed at the image portion of the blade nip and
produce a lubricating coating of a metal salt of a fatty acid
there. This lubricating coating limits wear on the blade nip. In
particular, after a stress run, or when the external additives have
sunk deeper in the toner, the metal salt particles adhere to the
toner particles more easily, because the surface of the toner
particles has been more exposed. In that state the loose aggregates
of the metal salt particles are formed more easily. Uneven wear on
the blade nip is therefore limited even after a stress run. This
may help control voids in images. [0022] Net Intensity of the Peak
for the Mg Element in the Toner in an X-Ray Fluorescence
Analysis
[0023] The toner according to this exemplary embodiment for
developing an electrostatic charge image contains the Mg element in
an amount such that in an x-ray fluorescence analysis of the toner,
the net intensity of the peak for the Mg element is 0.10 kcps or
more and 1.20 kcps or less. The net intensity of the peak for the
Mg element may be 0.15 kcps or more and 1.10 kcps or less in view
of better control of density unevenness and voids in the image.
Preferably, the net intensity of the peak for the Mg element is
0.20 kcps or more and 1.00 kcps or less.
[0024] The Mg element in the toner according to this exemplary
embodiment for developing an electrostatic charge image can be from
any source. Examples of sources include a magnesium flocculant,
such as magnesium chloride, and its residue and a magnesium salt
used as an additive.
[0025] The x-ray fluorescence analysis of the toner and the
measurement of the net intensity of the peak for the Mg element can
be as follows.
[0026] Approximately 5 g of the toner (including the external
additives) is compressed using a compression molding machine under
a load of 10 t for 60 seconds to give a 50-mm diameter and 2-mm
thick disk. This sample disk is qualitatively and quantitatively
analyzed for chemical elements therein under the conditions below
using a scanning x-ray fluorescence spectrometer (Rigaku ZSX Primus
II). In the resulting spectrum, the net intensity of the peak for
the Mg element (in kcps, kilo-counts per second) is determined.
[0027] Tube voltage: 40 kV [0028] Tube current: 70 mA [0029]
Anticathode material: Rhodium [0030] Duration of measurement: 15
minutes [0031] Spot diameter: 10 mm
External Additives
[0031] [0032] Particles of at Least One Compound Represented by
Formula (1)
[0033] The toner according to this exemplary embodiment for
developing an electrostatic charge image contains, as an external
additive, particles of at least one compound represented by formula
(1) (particles of formula (1)).
MTiO.sub.3 (1)
[0034] In formula (1), M represents at least one selected from the
group consisting of Ca, Sr, and Ba.
[0035] In view of better control of density unevenness and voids in
the image, the M in formula (1) may be Ca.
[0036] That is, the particles of formula (1) may be particles of
calcium titanate.
[0037] The particles of formula (1) only need to contain 50% by
mass or more the compound represented by formula (1). The
percentage of the compound represented by formula (1) may be 80% by
mass or more, preferably 90% by mass or more, more preferably 95%
by mass or more and 100% by mass or less.
[0038] The average primary-particle diameter of the particles of
formula (1) may be 10 nm or more and 5,000 nm or less. This may
also lead to better control of density unevenness and voids in the
image. Preferably, the average primary-particle diameter of the
particles of formula (1) is 30 nm or more and 3,000 nm or less,
more preferably 50 nm or more and 1,000 nm or less, even more
preferably 60 nm or more and 500 nm or less, in particular 70 nm or
more and 130 nm or less.
[0039] In this exemplary embodiment, the diameter of particles of
an external additive (average primary-particle diameter) is the
diameter of circles having the same area as the images of primary
particles of the additive (so-called equivalent circular diameter).
This diameter can be determined by taking an electron microscope
image of a toner containing the external additive of interest, such
as particles of formula (1) or silica particles, and analyzing at
least 300 primary particles of the additive on the toner particles
on the image. From the analysis, the frequency-based distribution
of diameters of primary particles is determined. The diameter at
which the cumulative number of primary particles from the smallest
diameter is 50% is the average primary-particle diameter of the
external additive.
[0040] The ratio D/d1 between the volume-average diameter D of the
toner particles, described later herein, and the average
primary-particle diameter d1 of the particles of formula (1) may be
1.2 or more and 200 or less. This may also lead to better control
of density unevenness and voids in the image. Preferably, the ratio
D/d1 is 1.9 or more and 200 or less, more preferably 10 or more and
100 or less, even more preferably 30 or more and 80 or less.
[0041] The amount of the particles of formula (1) in the toner
according to this exemplary embodiment for developing an
electrostatic charge image may be 0.01 parts by mass or more and
2.0 parts by mass or less per 100 parts by mass of the toner
particles. This may also lead to better control of density
unevenness and voids in the image. Preferably, the amount of the
particles of formula (1) is 0.02 parts by mass or more and 1.0 part
by mass or less, more preferably 0.05 parts by mass or more and 0.5
parts by mass or less, even more preferably 0.08 parts by mass or
more and 0.2 parts by mass or less.
Particles of a Metal Salt of a Fatty Acid
[0042] The toner according to this exemplary embodiment for
developing an electrostatic charge image contains, as another
external additive, particles of a metal salt of a fatty acid (metal
salt particles).
[0043] The metal salt particles can be, for example, particles of a
salt formed by a fatty acid (e.g., stearic acid, 12-hydroxystearic
acid, behenic acid, montanic acid, lauric acid, or some other
organic acid) and a metal (e.g., calcium, zinc, magnesium,
aluminum, or some other metal (such as Na or Li)).
[0044] Specific examples of metal salt particles include particles
of salts such as zinc stearate, magnesium stearate, calcium
stearate, iron stearate, copper stearate, magnesium palmitate,
calcium palmitate, manganese oleate, zinc oleate, zinc laurate, and
zinc palmitate.
[0045] Of these, particles of a zinc salt of a fatty acid may lead
to better control of density unevenness and voids in the image and
may give the toner better characteristics, for example lubricity,
hydrophobicity, and wettability. Preferably, the metal salt
particles are particles of zinc stearate, zinc oleate, zinc
laurate, or zinc palmitate, more preferably particles of zinc
stearate.
[0046] The metal salt particles may be a mixture of particles of
different metal salts of a fatty acid. The metal salt particles,
furthermore, may be particles of a metal salt of a fatty acid and
of an extra component. Examples of extra components include higher
aliphatic alcohols. The metal salt particles, however, contain 10%
by mass or more a metal salt of a fatty acid. The percentage of the
metal salt of a fatty acid may be 50% by mass or more, preferably
80% by mass or more, more preferably 90% by mass or more, even more
preferably 95% by mass or more and 100% by mass or less.
[0047] In view of better control of density unevenness and voids in
the image, the volume-average diameter of the metal salt particles
may be 0.3 .mu.m or more and 10 .mu.m or less. Preferably, the
volume-average diameter of the metal salt particles is 0.5 .mu.m or
more and 8 .mu.m or less, more preferably 2 .mu.m or more and 6
.mu.m or less.
[0048] The volume-average diameter of the metal salt particles can
be measured as follows.
[0049] That is, the measuring instrument is LA-920 laser
diffraction/scattering particle size analyzer (HORIBA, Ltd.).
Parameter setting and analysis of measured data are carried out on
HORIBA LA-920 for Windows.RTM. WET (LA-920) Ver. 2.02 (HORIBA,
Ltd.), dedicated software that comes with LA-920. The measuring
solvent is deionized water from which solid and other impurities
have been removed.
[0050] The amount of the metal salt particles may be 0.01 parts by
mass or more and 5 parts by mass or less per 100 parts by mass of
the toner particles. This may also lead to better control of
density unevenness and voids in the image. Preferably, the amount
of the metal salt particles is 0.02 parts by mass or more and 3.0
parts by mass or less, more preferably 0.03 parts by mass or more
and 1.0 part by mass or less, even more preferably 0.05 parts by
mass or more and 0.5 parts by mass or less.
[0051] The ratio D/d2 between the volume-average diameter D of the
toner particles, described later herein, and the volume-average
diameter d2 of the metal salt particles may be 0.1 or more and 50
or less. This may also lead to better control of density unevenness
and voids in the image. Preferably, the ratio D/d2 is 0.2 or more
and 20 or less, more preferably 0.5 or more and 10 or less, even
more preferably 0.7 or more and 3 or less.
[0052] The toner according to this exemplary embodiment for
developing an electrostatic charge image may contain, as an extra
external additive, particles other than the particles of formula
(1) and the metal salt particles.
[0053] The number-average diameter of the particles used as an
extra external additive in addition to the particles of formula (1)
and the metal salt particles may be 5 nm or more and 400 nm or
less, preferably 10 nm or more and 200 nm or less.
[0054] Any type of particles may be used as an extra external
additive in addition to the particles of formula (1) and the metal
salt particles. For example, the extra external additive may be
inorganic or organic particles.
[0055] Examples of inorganic particles include SiO.sub.2,
TiO.sub.2, Al.sub.2O.sub.3, CuO, ZnO, SnO.sub.2, CeO.sub.2,
Fe.sub.2O.sub.3, MgO, BaO, CaO, K.sub.2O, Na.sub.2O, ZrO.sub.2,
CaO.SiO.sub.2, K.sub.2O.(TiO.sub.2).sub.n,
Al.sub.2O.sub.3.2SiO.sub.2, CaCO.sub.3, MgCO.sub.3, BaSO.sub.4,
MgSO.sub.4, and SrTiO.sub.3.
[0056] Examples of organic particles include resin particles
(particles of silicone resins, polystyrene, polymethyl methacrylate
(PMMA), melamine resins, etc.) and particles of active cleaning
agents (e.g., particles of metal salts of higher fatty acids,
typically zinc stearate, and particles of fluoropolymers).
[0057] Silica particles, titania particles, and silica-titania
composite particles are preferred, and silica particles are more
preferred.
[0058] The amount of extra external additives used in addition to
the particles of formula (1) and the metal salt particles may be
0.01 parts by mass or more and 10 parts by mass or less per 100
parts by mass of the toner particles. This may also lead to better
control of density unevenness and voids in the image. Preferably,
the amount of extra external additives is 0.05 parts by mass or
more and 5 parts by mass or less, more preferably 0.1 parts by mass
or more and 2 parts by mass or less.
Toner Particles
[0059] The toner contains toner particles containing at least one
binder resin. Optionally, the toner particles may contain a
coloring agent, a release agent, and/or other additives.
Binder Resin(s)
[0060] In view of the strength of the image and better control of
unevenness in the density of the image, the binder resin may
include an amorphous resin and a crystalline resin.
[0061] An amorphous resin as referenced herein represents a resin
whose thermoanalytical profile as measured by differential scanning
calorimetry (DSC) has no clear endothermic peak and only has
stepwise endothermic changes. An amorphous resin is solid at room
temperature and thermoplasticizes at temperatures equal to or
higher than its glass transition temperature.
[0062] A crystalline resin as referenced herein represents a resin
whose DSC profile has a clear endothermic peak rather than stepwise
endothermic changes.
[0063] To take a specific example, if a crystalline resin is
analyzed by DSC at a heating rate of 10.degree. C./min, the DSC
profile has an endothermic peak with a half width of 10.degree. C.
or narrower. If an amorphous resin is analyzed likewise, the DSC
profile has an endothermic peak with a half width broader than
10.degree. C. or no clear endothermic peak.
[0064] The amorphous resin may be as described below.
[0065] Examples of amorphous resins include known amorphous resins,
such as amorphous polyester resins, amorphous vinyl (e.g.,
styrene-acrylic) resins, epoxy resins, polycarbonate resins, and
polyurethane resins. Of these, the use of an amorphous polyester or
amorphous vinyl (styrene-acrylic in particular) resin, preferably
an amorphous polyester resin, may lead to even better control of
density unevenness and voids in the image.
[0066] A combination of amorphous polyester and styrene-acrylic
resins may also be used.
[0067] An example of an amorphous polyester resin is an
polycondensate of a polycarboxylic acid and a polyhydric alcohol.
Both commercially available and synthesized amorphous polyester
resins can be used.
[0068] Examples of polycarboxylic acids include aliphatic
dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid,
fumaric acid, citraconic acid, itaconic acid, glutaconic acid,
succinic acid, an alkenylsuccinic acid, adipic acid, and sebacic
acid), aromatic dicarboxylic acids (e.g., terephthalic acid,
isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid),
and anhydrides and lower-alkyl (e.g., C1-5 alkyl) esters thereof.
Of these, aromatic dicarboxylic acids are preferred.
[0069] A combination of a dicarboxylic acid and a crosslinked or
branched carboxylic acid having three or more carboxylic groups may
also be used. Examples of carboxylic acids having three or more
carboxylic groups include trimellitic acid, pyromellitic acid, and
anhydrides and lower-alkyl (e.g., C1-5 alkyl) esters thereof.
[0070] One polycarboxylic acid may be used alone, or two or more
may be used in combination.
[0071] Examples of polyhydric alcohols include aliphatic diols
(e.g., ethylene glycol, diethylene glycol, triethylene glycol,
propylene glycol, butanediol, hexanediol, and neopentyl glycol),
alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and
hydrogenated bisphenol A), and aromatic diols (e.g., ethylene oxide
adducts of bisphenol A and propylene oxide adducts of bisphenol A).
Of these, aromatic diols and alicyclic diols are preferred, and
aromatic diols are more preferred.
[0072] A combination of a diol and a crosslinked or branched
polyhydric alcohol having three or more hydroxyl groups may also be
used. Examples of polyhydric alcohols having three or more hydroxyl
groups include glycerol, trimethylolpropane, and
pentaerythritol.
[0073] One polyhydric alcohol may be used alone, or two or more may
be used in combination.
[0074] The production of the amorphous polyester resin can be by a
known method. A specific example is to polymerize raw materials at
a temperature of 180.degree. C. or more and 230.degree. C. or less.
The reaction system may optionally be evacuated to remove the water
and alcohol that are produced as condensation proceeds. If the
raw-material monomers do not dissolve or are not miscible together
at the reaction temperature, a high-boiling solvent may be added as
a solubilizer to make the monomers dissolve. In that case, the
solubilizer is removed by distillation during the polycondensation.
If one monomer is not miscible with the other(s) in
copolymerization, this monomer may be first condensed with an acid
or alcohol to be polycondensed therewith, and then the product may
be polycondensed with the remaining ingredient(s).
[0075] A styrene-acrylic resin is also an example of a binder
resin, an amorphous binder resin in particular.
[0076] A styrene-acrylic resin is a copolymer of at least a styrene
monomer (monomer having the styrene structure) and a (meth)acrylic
monomer (monomer having a (meth)acrylic group, preferably a
(meth)acryloxy group). Examples of styrene-acrylic resins include
copolymers of a styrene monomer and a (meth)acrylate monomer.
[0077] A styrene-acrylic resin has an acrylic-resin substructure
formed by the polymerization of an acrylic monomer, a methacrylic
monomer, or both. The expression "(meth)acrylic" encompasses both
"acrylic" and "methacrylic," and the expression "(meth)acrylate"
encompasses both an "acrylate" and a "methacrylate."
[0078] Specific examples of styrene monomers include styrene,
alkylated styrenes (e.g., a-methylstyrene, 2-methylstyrene,
3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene,
and 4-ethylstyrene), halogenated styrenes (e.g., 2-chlorostyrene,
3-chlorostyrene, and 4-chlorostyrene), and vinylnaphthalene. One
styrene monomer may be used alone, or two or more may be used in
combination.
[0079] Of these, styrene is highly reactive and readily available.
Its reaction, moreover, is easy to control.
[0080] Specific examples of (meth)acrylic monomers include
(meth)acrylic acid and (meth)acrylates. Examples of (meth)acrylates
include alkyl (meth)acrylates (e.g., methyl (meth)acrylate, ethyl
(meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate,
n-pentyl (meth)acrylate, n-hexyl acrylate, n-heptyl (meth)acrylate,
n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)
acrylate, n-lauryl (meth) acrylate, n-tetradecyl (meth) acrylate,
n-hexadecyl (meth) acrylate, n-octadecyl (meth)acrylate, isopropyl
(meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate,
isopentyl (meth)acrylate, amyl (meth)acrylate, neopentyl
(meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth) acrylate,
isooctyl (meth) acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl
(meth)acrylate, and t-butylcyclohexyl (meth)acrylate), aryl
(meth)acrylates (e.g., phenyl (meth)acrylate, biphenyl
(meth)acrylate, diphenylethyl (meth) acrylate, t-butylphenyl (meth)
acrylate, and terphenyl (meth)acrylate), dimethylaminoethyl (meth)
acrylate, diethylaminoethyl (meth) acrylate, methoxyethyl (meth)
acrylate, 2-hydroxyethyl (meth) acrylate, .beta.-carboxyethyl
(meth)acrylate, and (meth)acrylamides. One (meth)acrylic monomer
may be used alone, or two or more may be used in combination.
[0081] Of these (meth)acrylates, those having a C2-14 (preferably
C2-10, more preferably C3-8) alkyl group may help improve fixation
of the image.
[0082] n-butyl (meth)acrylate is preferred, and n-butyl acrylate is
more preferred.
[0083] The ratio between the styrene monomer and the (meth)acrylic
monomer in the copolymer (by mass; styrene monomer/(meth)acrylic
monomer) is not critical. For example, the ratio between the two
types of monomers in the copolymer may be between 85/15 and
70/30.
[0084] A crosslinked styrene-acrylic resin may also be used. An
example is a copolymer of at least a styrene monomer, a
(meth)acrylic monomer, and a crosslinking monomer.
[0085] An example of a crosslinking monomer is a crosslinking agent
that has two or more functional groups.
[0086] Examples of bifunctional crosslinking agents include divinyl
benzene, divinyl naphthalene, di(meth)acrylate compounds (e.g.,
diethylene glycol di(meth)acrylate, methylene bis(meth)acrylamide,
decanediol diacrylate, and glycidyl (meth)acrylate),
polyester-forming di(meth)acrylates, and
2-([1'-methylpropylideneamino]carboxyamino)ethyl methacrylate.
[0087] Examples of crosslinking agents having more than two
functional groups include tri(meth)acrylate compounds (e.g.,
pentaerythritol tri(meth)acrylate, trimethylolethane
tri(meth)acrylate, and trimethylolpropane tri(meth)acrylate),
tetra(meth)acrylate compounds (e.g., pentaerythritol
tetra(meth)acrylate and oligoester (meth)acrylates),
2,2-bis(4-methacryloxy, polyethoxyphenyl)propane, diallyl
phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl
trimellitate, and diaryl chlorendate.
[0088] The use of a (meth)acrylate compound having two or more
(meth)acrylic groups may help control the events of low image
density and uneven image density and may also help improve fixation
of the image. Preferably, the crosslinking monomer is a
di(meth)acrylate compound, more preferably a di(meth)acrylate
compound having a C6 to C20 alkylene group, even more preferably a
di(meth)acrylate compound having a linear C6 to C20 alkylene
group.
[0089] The ratio of the crosslinking monomer to all monomers in the
copolymer (by mass; crosslinking monomer/all monomers) is not
critical. For example, the ratio of the crosslinking monomer to all
monomers may be between 2/1,000 and 20/1,000.
[0090] How to produce the styrene-acrylic resin is not critical. A
wide variety of polymerization techniques (solution polymerization,
precipitation polymerization, suspension polymerization, bulk
polymerization, emulsion polymerization, etc.) can be used. The
polymerization reactions, furthermore, can be done by known
processes (batch, semicontinuous, continuous, etc.).
[0091] The styrene-acrylic resin may constitute 0% by mass or more
and 20% by mass or less of all binder resins in the toner
particles. Preferably, the styrene-acrylic resin content is 1% by
mass or more and 15% by mass or less, more preferably 2% by mass or
more and 10% by mass or less.
[0092] The amorphous resin may constitute 60% by mass or more and
98% by mass or less of all binder resins in the toner particles.
Preferably, the amorphous resin content is 65% by mass or more and
95% by mass or less, more preferably 70% by mass or more and 90% by
mass or less.
[0093] Some characteristics of the amorphous resin may be as
described below.
[0094] The glass transition temperature (Tg) of the amorphous resin
may be 50.degree. C. or more and 80.degree. C. or less, preferably
50.degree. C. or more and 65.degree. C. or less.
[0095] This glass transition temperature is that determined from
the DSC curve of the resin, which is measured by differential
scanning calorimetry (DSC). More specifically, this glass
transition temperature is the "extrapolated initial temperature of
glass transition" as in the methods for determining glass
transition temperatures set forth in JIS K7121: 1987 "Testing
Methods for Transition Temperatures of Plastics."
[0096] The weight-average molecular weight (Mw) of the amorphous
resin may be 5,000 or more and 1,000,000 or less, preferably 7,000
or more and 500,000 or less.
[0097] The number-average molecular weight (Mn) of the amorphous
resin may be 2,000 or more and 100,000 or less.
[0098] The molecular weight distribution, Mw/Mn, of the amorphous
resin may be 1.5 or more and 100 or less, preferably 2 or more and
60 or less.
[0099] These weight- and number-average molecular weights are those
measured by gel permeation chromatography (GPC). The analyzer is
Tosoh's HLC-8120 GPC chromatograph with Tosoh's TSKgel SuperHM-M
column (15 cm), and the eluate is tetrahydrofuran (THF). Comparing
the measured data with a molecular-weight calibration curve
prepared using monodisperse polystyrene standards gives the weight-
and number-average molecular weights.
[0100] The crystalline resin may be as described below.
[0101] Examples of crystalline resins include known crystalline
resins, such as crystalline polyester resins and crystalline vinyl
resins (e.g., polyalkylene resins and long-chain alkyl
(meth)acrylate resins). Of these, the use of a crystalline
polyester resin may lead to even better control of density
unevenness and voids in the image.
[0102] An example of a crystalline polyester resin is a
polycondensate of a polycarboxylic acid and a polyhydric alcohol.
Both commercially available and synthesized crystalline polyester
resins can be used.
[0103] Crystalline polyester resins made with linear aliphatic
polymerizable monomers may readily form a crystal structure
compared with those made with aromatic polymerizable monomers.
[0104] Examples of polycarboxylic acids include aliphatic
dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric
acid, adipic acid, suberic acid, azelaic acid, sebacic acid,
1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid,
1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid,
and 1,18-octadecanedicarboxylic acid), aromatic dicarboxylic acids
(e.g., dibasic acids, such as phthalic acid, isophthalic acid,
terephthalic acid, and naphthalene-2,6-dicarboxylic acid), and
anhydrides and lower-alkyl (e.g., C1-5 alkyl) esters thereof.
[0105] A combination of a dicarboxylic acid and a crosslinked or
branched carboxylic acid having three or more carboxylic groups may
also be used. Examples of carboxylic acids having three or more
carboxylic groups include aromatic carboxylic acids (e.g.,
1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid,
and 1,2,4-naphthalenetricarboxylic acid) and anhydrides and
lower-alkyl (e.g., C1-5 alkyl) esters thereof.
[0106] A combination of a dicarboxylic acid such as listed above
and a dicarboxylic acid having a sulfonic acid group or an
ethylenic double bond may also be used.
[0107] One polycarboxylic acid may be used alone, or two or more
may be used in combination.
[0108] Examples of polyhydric alcohols include aliphatic diols
(e.g., C7-20 linear aliphatic diols). Examples of aliphatic diols
include ethylene glycol, 1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,
1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol,
1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol,
1,18-octadecanediol, and 1,14-eicosanedecanediol. Of these
1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are
preferred.
[0109] A combination of a diol and a crosslinked or branched
alcohol having three or more hydroxyl groups may also be used.
Examples of alcohols having three or more hydroxyl groups include
glycerol, trimethylolethane, trimethylolpropane, and
pentaerythritol.
[0110] One polyhydric alcohol may be used alone, or two or more may
be used in combination.
[0111] Aliphatic diols may constitute 80 mol % or more of
polyhydric alcohols. Preferably, the percentage of aliphatic diols
is 90 mol % or more.
[0112] The melting temperature of the crystalline polyester resin
may be 50.degree. C. or more and 100.degree. C. or less, preferably
55.degree. C. or more and 90.degree. C. or less, more preferably
60.degree. C. or more and 85.degree. C. or less.
[0113] The melting temperature of the crystalline polyester resin
is the "peak melting temperature" of the resin as in the methods
for determining melting temperatures set forth in JIS K7121: 1987
"Testing Methods for Transition Temperatures of Plastics" and is
determined from the DSC curve of the resin, which is measured by
differential scanning calorimetry (DSC).
[0114] The weight-average molecular weight (Mw) of the crystalline
polyester resin may be 6,000 or more and 35,000 or less.
[0115] The production of the crystalline polyester resin can be by
a known method. For example, it may be produced in the same way as
the amorphous polyester resin.
[0116] The crystalline polyester resin may be a polymer formed by a
linear aliphatic .alpha.,.omega.-dicarboxylic acid and a linear
aliphatic .alpha.,.omega.-diol. This type of polymer may form a
crystal structure readily, and, furthermore, using this type of
polymer with an amorphous polyester resin may help improve the
fixation of the image by virtue of high miscibility between the
resins.
[0117] The linear aliphatic .alpha.,.omega.-dicarboxylic acid may
be one having a C3 to C14 alkylene group between the two carboxy
groups. Preferably, the number of carbon atoms in the alkylene
group is 4 or more and 12 or less, more preferably 6 or more and 10
or less.
[0118] Examples of linear aliphatic .alpha.,.omega.-dicarboxylic
acids include succinic acid, glutaric acid, adipic acid,
1,6-hexanedicarboxylic acid (commonly known as suberic acid),
1,7-heptanedicarboxylic acid (commonly known as azelaic acid),
1,8-octanedicarboxylic acid (commonly known as sebacic acid),
1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid,
1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid,
and 1,18-octadecanedicarboxylic acid. Of these,
1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid,
1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and
1,10-decanedicarboxylic acid are preferred.
[0119] One linear aliphatic .alpha.,.omega.-dicarboxylic acid may
be used alone, or two or more may be used in combination.
[0120] The linear aliphatic .alpha.,.omega.-diol may be one having
a C3 to C14 alkylene group between the two hydroxy groups.
Preferably, the number of carbon atoms in the alkylene group is 4
or more and 12 or less, more preferably 6 or more and 10 or
less.
[0121] Examples of linear aliphatic .alpha.,.omega.-diols include
ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol,
1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and
1,18-octadecanediol. Of these, 1,6-hexanediol, 1,7-heptanediol,
1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are
preferred.
[0122] One linear aliphatic .alpha.,.omega.-diol may be used alone,
or two or more may be used in combination.
[0123] Preferably, the polymer formed by a linear aliphatic
.alpha.,.omega.-dicarboxylic acid and a linear aliphatic
.alpha.,.omega.-diol is polymer(s) formed by at least one selected
from the group consisting of 1,6-hexanedicarboxylic acid,
1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid,
1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid and
at least one selected from the group consisting of 1,6-hexanediol,
1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and
1,10-decanediol, more preferably a polymer formed by
1,10-decanedicarboxylic acid and 1,6-hexanediol. This type of
polymer may form a crystal structure more readily, and,
furthermore, using this type of polymer with an amorphous polyester
resin may lead to further improved fixation of the image by virtue
of higher miscibility between the resins.
[0124] The crystalline resin may constitute 1% by mass or more and
20% by mass or less of all binder resins in the toner particles.
Preferably, the crystalline resin content is 2% by mass or more and
15% by mass or less, more preferably 3% by mass or more and 10% by
mass or less.
Other Binder Resins
[0125] Other binder resins that may be used include homopolymers of
monomers such as ethylenic unsaturated nitriles (e.g.,
acrylonitrile and methacrylonitrile), vinyl ethers (e.g., vinyl
methyl ether and vinyl isobutyl ether), vinyl ketones (e.g., vinyl
methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone),
and olefins (e.g., ethylene, propylene, and butadiene) and
copolymers of two or more such monomers.
[0126] Non-vinyl resins, such as epoxy resins, polyurethane resins,
polyamide resins, cellulose resins, polyether resins, and modified
rosin, mixtures of non-vinyl and vinyl resins, and graft copolymers
obtained by polymerizing a vinyl monomer in the presence of a
non-vinyl resin are also examples of binder resins that may be
used.
[0127] One such binder resin may be used alone, or two or more may
be used in combination.
[0128] The binder resin content may be 40% by mass or more and 95%
by mass or less of the toner particles as a whole. Preferably, the
binder resin content is 50% by mass or more and 90% by mass or
less, more preferably 60% by mass or more and 85% by mass or
less.
Release Agent
[0129] The toner particles may contain a release agent.
[0130] Examples of release agents include hydrocarbon waxes;
natural waxes, such as carnauba wax, rice wax, and candelilla wax;
synthesized or mineral/petroleum waxes, such as montan wax; and
ester waxes, such as fatty acid esters and montanates. Other
release agents may also be used.
[0131] The use of an ester wax may lead to better control of
density unevenness and voids in the image. Using an ester wax with
an amorphous polyester resin, furthermore, may help improve the
fixation of the image by virtue of high miscibility between the wax
and the resin. Ester waxes formed by a C10 to C30 higher fatty acid
and a monohydric or polyhydric Cl to C30 alcohol component are
preferred.
[0132] An ester wax is a wax having an ester bond. An ester wax can
be used regardless of whether it is a monoester, diester, triester,
or tetraester, and any known naturally occurring or synthetic ester
wax can be used.
[0133] An example of an ester wax is an ester compound formed by a
higher fatty acid (e.g., a C10 or longer fatty acid) and a
monohydric or polyhydric aliphatic alcohol (e.g., a C8 or longer
aliphatic alcohol) and having a melting temperature of 60.degree.
C. or more and 110.degree. C. or less (preferably 65.degree. C. or
more and 100.degree. C. or less, more preferably 70.degree. C. or
more and 95.degree. C. or less).
[0134] Examples of ester waxes, furthermore, include ester
compounds formed by a higher fatty acid (e.g., caprylic acid,
capric acid, lauric acid, myristic acid, palmitic acid, stearic
acid, arachidic acid, behenic acid, or oleic acid) and an alcohol
(monohydric alcohol, such as methanol, ethanol, propanol,
isopropanol, butanol, capryl alcohol, lauryl alcohol, myristyl
alcohol, cetyl alcohol, stearyl alcohol, or oleyl alcohol; or
polyhydric alcohol, such as glycerol, ethylene glycol, propylene
glycol, sorbitol, or pentaerythritol). Specific examples include
carnauba wax, rice wax, candelilla wax, jojoba oil, Japan wax,
beeswax, ibotaro wax (wax produced by Ericerus pela), lanoline, and
montanate waxes.
[0135] The melting temperature of the release agent may be
50.degree. C. or more and 110.degree. C. or less, preferably
60.degree. C. or more and 100.degree. C. or less.
[0136] The melting temperature of the release agent is the "peak
melting temperature" of the agent as in the methods for determining
melting temperatures set forth in JIS K7121: 1987 "Testing Methods
for Transition Temperatures of Plastics" and is determined from the
DSC curve of the agent, which is measured by differential scanning
calorimetry (DSC).
[0137] The release agent content may be 1% by mass or more and 20%
by mass or less of the toner particles as a whole. Preferably, the
release agent content is 5% by mass or more and 15% by mass or
less.
Other Additives
[0138] Examples of other additives include well-known additives,
such as magnetic substances, charge control agents, and inorganic
powders. Such additives, if used, are contained in the toner
particles as internal additives. Form of Domains of the Crystalline
Resin in the Toner Particles
[0139] If the toner particles contain an amorphous resin and a
crystalline resin as binder resins, the toner according to this
exemplary embodiment for developing an electrostatic charge image
may be configured such that in a cross-sectional observation of the
toner particles, at least two (preferably at least three) domains
of the crystalline resin meet conditions (A) , (B1)/(B2) , (C) ,
and (D). For conditions (B1) and (B2), the at least two domains of
the crystalline resin only need to meet at least one of them.
[0140] Condition (A): Each domain of the crystalline resin has an
aspect ratio of 5 or more and 40 or less.
[0141] Condition (B1): Each domain of the crystalline resin
measures 0.5 .mu.m or more and 1.5 .mu.m or less along its major
axis.
[0142] Condition (B2): Each domain of the crystalline resin
measures, along its major axis, 10% or more and 30% or less of the
longest diameter of the toner particle.
[0143] Condition (C): A line extended from the major axis of each
domain of the crystalline resin makes an angle of 60.degree. or
more and 90.degree. or less with the tangent to the surface of the
toner particle at the point of contact between the extended line
and the surface.
[0144] Condition (D): Lines extended from the major axis of the two
domains of the crystalline resin cross each other at an angle of
45.degree. or more and 90.degree. or less.
[0145] Images formed with much toner thereon can be uneven in
gloss. A toner according to this exemplary embodiment in this
configuration may help address this, presumably for the following
reasons.
[0146] If a cross-section of a toner particle has at least two
domains of the crystalline resin that meet conditions (A), (B1),
(C), and (D), the toner particle tends to conduct heat nearly
uniformly. When an image formed by a toner containing such toner
particles is fixed, therefore, it may be unlikely that the toner
particles melt unevenly.
[0147] The situation in which a toner particle meets these
conditions translates into that two domains of the crystalline
resin having a large aspect ratio, i.e., ellipsoidal or
needle-shaped and long along their major axis, extend from near the
surface to the inside of the toner particle and cross each other
(see FIG. 3).
[0148] When an image formed by a toner containing such toner
particles is fixed, the ellipsoidal or needle-shaped domains of the
crystalline resin melt in response to the heat applied to the toner
particles, helping the heat penetrate from the surface to the
inside of the toner particles quickly. As a result, the heat may
spread throughout the inside of the toner particles nearly
uniformly, and the toner particles may be encouraged to melt nearly
evenly throughout the inside thereof.
[0149] Likewise, if a cross-section of a toner particle has at
least two domains of the crystalline resin that meet conditions
(A), (B2), (C), and (D), the toner particle tends to conduct heat
nearly uniformly. When an image formed by a toner containing such
toner particles is fixed, therefore, it may be unlikely that the
toner particles melt unevenly.
[0150] The situation in which a toner particle meets these
conditions translates into that two domains of the crystalline
resin having a large aspect ratio, i.e., ellipsoidal or
needle-shaped and long along their major axis, extend from near the
surface to the inside of the toner particle and cross each other
(see FIG. 3). When an image formed by a toner containing such toner
particles is fixed, therefore, the heat applied to the toner
particles may spread throughout the inside of the toner particles
nearly uniformly, and the toner particles may be encouraged to melt
nearly evenly throughout the inside thereof.
[0151] Presumably for these reasons, a toner according to this
exemplary embodiment in the above configuration may help address
the problem of uneven image gloss that can occur when an image is
formed with much toner thereon.
[0152] The meanings of the symbols in FIG. 3 are as follows.
[0153] TN: Toner particle
[0154] Amo: Amorphous resin
[0155] Cry: Domains of the crystalline resin
[0156] L.sub.cry: Length of the domain of the crystalline resin
along its major axis
[0157] L.sub.T: Longest diameter of the toner particle
[0158] .theta..sub.A: Angle between a line extended from the major
axis of the domain of the crystalline resin and the tangent to the
surface of the toner particle at the point of contact between the
extended line and the surface
[0159] .theta..sub.B: Angle between lines extended from the major
axis of two domains of the crystalline resin
[0160] The following describes the individual conditions. Condition
(A)
[0161] Each domain of the crystalline resin has an aspect ratio of
5 or more and 40 or less.
[0162] In view of better control of unevenness in the gloss of the
image, the aspect ratio of each domain of the crystalline resin may
be 10 or more and 40 or less.
[0163] In this context, the aspect ratio of a domain of the
crystalline resin is the ratio between the lengths of the domain of
the crystalline resin along its major and minor axes (length along
the major axis/length along the minor axis).
[0164] The length of a domain of the crystalline resin along its
major axis is the longest length of the domain of the crystalline
resin.
[0165] The length of a domain of the crystalline resin along its
minor axis is the longest length of the domain of the crystalline
resin in the direction perpendicular to a line extended from the
major axis of the domain.
Condition (B1)
[0166] Each domain of the crystalline resin measures 0.5 .mu.m or
more and 1.5 .mu.m or less along its major axis (see L.sub.cry in
FIG. 3).
[0167] The length of each domain of the crystalline resin along its
major axis may be 0.8 .mu.m or more and 1.5 .mu.m or less. This may
also lead to better control of unevenness in the gloss of the
image.
Condition (B2)
[0168] At least one of the two domains of the crystalline resin
measures, along its major axis (see L.sub.cry in FIG. 3), 10% or
more and 30% or less of the longest diameter of the toner particle
(see L.sub.T in FIG. 3).
[0169] The percentage of the length of the domain(s) of the
crystalline resin along its major axis to the longest diameter of
the toner particle may be 13% or more and 30% or less, preferably
17% or more and 30% or less. This may also lead to better control
of unevenness in the gloss of the image.
[0170] The longest diameter of a toner particle is the longest
possible length of a segment between two points on the contour of a
cross-section of the toner particle (so-called major diameter).
Condition (C)
[0171] A line extended from the major axis of each domain of the
crystalline resin makes an angle of 60.degree. or more and
90.degree. or less with the tangent to the surface of the toner
particle (i.e., the outer edge of the toner particle) at the point
of contact between the extended line and the surface (see
.theta..sub.A in FIG. 3).
[0172] The angle between a line extended from the major axis of
each domain of the crystalline resin and the tangent to the surface
of the toner particle at the point of contact between the extended
line and the surface may be 75.degree. or more and 90.degree. or
less. This may also lead to better control of unevenness in the
gloss of the image.
Condition (D)
[0173] Lines extended from the major axis of the two domains of the
crystalline resin cross each other at an angle of 45.degree. or
more and 90.degree. or less (see .theta..sub.B in FIG. 3).
[0174] The angle between lines extended from the major axis of the
two domains of the crystalline resin (see .theta..sub.B in FIG. 3)
may be 60.degree. or more and 90.degree. or less. This may also
lead to better control of unevenness in the gloss of the image.
[0175] The toner particles meeting these conditions may constitute
40% by number or more of all toner particles. This may also lead to
better control of unevenness in the gloss of the image. Preferably,
the percentage of toner particles meeting the above conditions is
70% by number or more, more preferably 80% by number or more, even
more preferably 90% by number or more. It would be ideal if 100% by
number of the toner particles would meet the above conditions.
[0176] With increasing percentage of toner particles meeting the
above conditions, the toner particles as a whole may become more
likely to melt nearly uniformly, and unevenness in the gloss of the
image may be controlled better.
[0177] It should be noted that a toner particle may have three or
more domains of the crystalline resin that meet conditions (A),
(B1), and (C) or conditions (A), (B2), and (C). In that case, this
toner particle is considered to meet the above conditions if any
two of the domains of the crystalline resin meet condition (D).
Cross-Sectional Observation of Toner Particles
[0178] Whether a toner particle meets conditions (A), (B1)/(B2),
(C), and (D) can be determined by observing a cross-section of the
toner particle as follows.
[0179] The toner particles (with adhering external additives
thereon) are mixed into epoxy resin, and the epoxy resin is cured.
The resulting solid is sliced using an ultramicrotome (Leica
Ultracut UCT) to give a thin specimen having a thickness of 80 nm
or more and 130 nm or less. The specimen is stained with ruthenium
tetroxide for 3 hours in a desiccator at 30.degree. C. A STEM image
(magnification, 20,000) of the stained specimen is obtained through
transmission imaging using an ultrahigh-resolution field-emission
scanning electron microscope (FE-SEM; Hitachi High-Technologies
S-4800).
[0180] Then domains in a toner particle are examined to identify,
by contrast and shape, whether each of them is a domain of the
crystalline resin or some other resin (amorphous resin, release
agent (if used), etc.). In the SEM image, the binder resins, which
are rich in double bonds compared with the release agent, appear
stained darker with ruthenium tetroxide. Likewise, the amorphous
resin appears stained darker than the crystalline resin. By using
this, one can distinguish between domains of the release agent and
other resins and between domains of the crystalline and amorphous
resins.
[0181] To be more specific, domains of the release agent are
stained the lightest with ruthenium, domains of the crystalline
resin (e.g., crystalline polyester resin) the second lightest, and
domains of the amorphous resin (e.g., amorphous polyester resin)
are stained the darkest. The contrast may be adjusted to make
domains of the release agent look white, domains of the amorphous
resin look black, and domains of the crystalline resin look light
gray. Now each domain can be identified by color.
[0182] The ruthenium-stained domains of the crystalline resin are
then examined to determine whether or not the toner particle meets
conditions (A), (B1)/(B2), (C), and (D).
[0183] To determine the percentage of toner particles meeting the
conditions, the above observation is made on 100 toner particles.
Then the percentage of toner particles meeting the conditions is
determined by calculation.
[0184] It should be noted that the SEM image usually includes
different sizes of cross-sections of toner particles. The
observations are made on cross-sections whose diameter is 85% or
more of the volume-average diameter of the toner particles. The
diameter of a cross-section of a toner particle in this context is
the longest possible length of a segment between two points on the
contour of the cross-section of a toner particle (so-called major
diameter).
[0185] In a cross-section of a toner particle in which at least two
domains of the crystalline resin meet condition (A), at least one
of conditions (B1) and (B2), condition (C), and condition (D),
furthermore, the domains of the release agent, if used, may be at
50 nm or deeper inside from the surface of the toner particle. In
other words, when a cross-section of a toner particle meeting the
above conditions is observed, the shortest distance between the
domains of the release agent in the toner particle and the surface
(outer edge) of the toner particle may be 50 nm or more.
[0186] The situation in which the domains of the release agent are
at 50 nm or deeper inside from the surface of the toner particle
means that no domain of the release agent is exposed on the surface
of the toner particle. If there is any exposed domain of the
release agent on the surface of a toner particle, the external
additives adhere and concentrate preferentially where the release
agent is exposed. Ensuring the domains of the release agent are at
50 nm or deeper inside from the surface of the toner particles
therefore encourages the external additives to adhere to the toner
particles nearly uniformly, hence a lower likelihood of uneven
melting of the toner particles during fixation. As a result,
unevenness in the gloss of the image may be controlled even
better.
[0187] Whether a toner particle has the domains of the release
agent at 50 nm or deeper inside from the surface thereof can be
checked by observing a cross-section of the toner particle by the
method described above.
[0188] For those toner particles that have at least two domains of
the crystalline resin meeting the above conditions and have the
domains of the release agent at 50 nm or deeper inside from the
surface thereof, too, the percentage may be 40% by number or more
of all toner particles. This may also lead to better control of
unevenness in the gloss of the image. Preferably, the percentage of
such toner particles is 70% by number or more, more preferably 80%
by number or more, even more preferably 90% by number or more. It
would be ideal if 100% by number of the toner particles would be
such.
Characteristics and Other Details of the Toner Particles
[0189] The toner particles may be single-layer toner particles or
may be so-called core-shell toner particles, i.e., toner particles
formed by a core section (core particle) and a coating layer that
covers the core section (shell layer).
[0190] Core-shell toner particles may be formed by, for example, a
core section made with the binder resin and optionally additives,
such as a coloring agent and a release agent, and a coating layer
made with the binder resin.
[0191] The volume-average diameter (D50v) of the toner particles
may be 2 .mu.m or more and 15 .mu.m or less, preferably 4 .mu.m or
more and 8 .mu.m or less, more preferably 4 .mu.m or more and 7
.mu.m or less, even more preferably 5 .mu.m or more and 6.5 .mu.m
or less.
[0192] It should be noted that the average diameters and geometric
standard deviations of toner particles indicated herein are those
measured using Coulter Multisizer II (Beckman Coulter) and
ISOTON-II electrolyte (Beckman Coulter).
[0193] For measurement, a sample of the toner particles weighing
0.5 mg or more and 50 mg or less is added to 2 ml of a 5% aqueous
solution of a dispersing surfactant (e.g., a sodium alkylbenzene
sulfonate). The resulting dispersion is added to 100 ml or more and
150 ml or less of the electrolyte.
[0194] The electrolyte with a suspended sample therein is sonicated
for 1 minute using a sonicator, and size distribution is measured
on 50000 sampled particles within a diameter range of 2 .mu.m to 60
.mu.m using Coulter Multisizer II with an aperture size of 100
.mu.m.
[0195] The measured distribution is divided into segments by
particle size (channels), and the cumulative distribution of volume
and that of frequency are plotted starting from the smallest
diameter. The particle diameter at which the cumulative volume is
16% and that at which the cumulative frequency is 16% are defined
as volume diameter D16v and number diameter D16p, respectively, of
the toner particles. The particle diameter at which the cumulative
volume is 50% and that at which the cumulative frequency is 50% are
defined as the volume-average diameter D50v and cumulative
number-average diameter D50p, respectively, of the toner particles.
The particle diameter at which the cumulative volume is 84% and
that at which the cumulative frequency is 84% are defined as volume
diameter D84v and number diameter D84p, respectively, of the toner
particles.
[0196] These are used to calculate the geometric standard deviation
by volume (GSDv) and geometric standard deviation by number (GSDp).
GSDv is given by (D84v/D16v).sup.1/2, and GSDp is given by
(D84p/D16p).sup.1/2.
[0197] The average roundness of the toner particles may be 0.94 or
more and 1.00 or less, preferably 0.95 or more and 0.98 or
less.
[0198] The average roundness of the toner particles is given by
(circumference of the equivalent circle)/(circumference)
[(circumference of circles having the same projected area as
particle images)/(circumference of projected images of the
particles)]. Specifically, the average roundness of the toner
particles can be measured as follows.
[0199] First, a portion of the toner particles of interest is
collected by aspiration in such a manner that it will form a flat
stream. This flat stream is photographed with a flash to capture
the figures of the particles in a still image. The images of 3500
sampled particles are analyzed using a flow particle-image analyzer
(Sysmex FPIA-3000), and the average roundness is determined from
the results.
[0200] The toner according to this exemplary embodiment contains
external additives. Prior to these measurements, therefore, the
toner particles are isolated by removing the external additives.
The external additives can be removed by dispersing the toner in
water containing a surfactant and sonicating the resulting
dispersion.
Characteristics of the Toner
[0201] When the toner according to this exemplary embodiment is
analyzed with a differential scanning calorimeter (DSC), the
largest endothermic peak in the first run of heating may appear at
a temperature of 58.degree. C. or more and 75.degree. C. or less.
The toner may fix well at low temperatures when it has its largest
endothermic peak in the first heating run between 58.degree. C. to
75.degree. C.
[0202] The DSC analysis of the toner and the measurement of the
temperature at which the toner has its largest endothermic peak in
the first run of heating can be as follows.
[0203] The measuring instrument is PerkinElmer's DSC-7 differential
scanning calorimeter. The detector of the calorimeter is calibrated
for temperature by measuring the melting point of indium and zinc
and for enthalpy by measuring the melting enthalpy of indium. An
aluminum pan with a sample therein and a control empty pan are
heated from room temperature to 150.degree. C. at a rate of
10.degree. C./min. The resulting endothermic curve is examined to
find the temperature at which the curve has the largest endothermic
peak.
Production of the Toner
[0204] The following describes the production of a toner according
to this exemplary embodiment.
[0205] A toner according to this exemplary embodiment can be
obtained by producing the toner particles and then adding the
external additives to the toner particles.
[0206] The production of the toner particles can be by a dry
process (e.g., kneading and milling) or wet process (e.g.,
aggregation and coalescence, suspension polymerization, or
dissolution and suspension). Any well-known dry or wet process may
be used to produce the toner particles.
[0207] Preferably, the toner particles are obtained by aggregation
and coalescence. This may help ensure that domains of a crystalline
resin meet the aforementioned conditions.
[0208] Specifically, if the toner particles are produced by, for
example, aggregation and coalescence, the production process can be
as follows.
[0209] A liquid dispersion of amorphous-resin particles, in which
particles of an amorphous resin have been dispersed, and a liquid
dispersion of crystalline-resin particles, in which particles of a
crystalline resin have been dispersed, are prepared (preparation of
liquid dispersions of resin particles).
[0210] The particles of an amorphous resin (optionally with a
coloring agent, a release agent, etc.) are allowed to aggregate in
the liquid dispersion of amorphous-resin particles (optionally
after liquid dispersions of a coloring agent, a release agent,
etc., are mixed therein). This gives first aggregates (formation of
first aggregates).
[0211] The resulting liquid dispersion of first aggregates is mixed
with the liquid dispersion of amorphous-resin particles and the
liquid dispersion of crystalline-resin particles (or with a mixture
of the liquid dispersion of amorphous-resin particles and the
liquid dispersion of crystalline-resin particles), and the
particles of amorphous and crystalline resins in the mixture are
allowed to aggregate on the surface of the first aggregates. This
is repeated twice or more to give second aggregates (formation of
second aggregates).
[0212] The resulting liquid dispersion of second aggregates is
mixed with the liquid dispersion of amorphous-resin particles, and
the particles of an amorphous resin in the mixture are allowed to
aggregate on the surface of the second aggregates. This gives third
aggregates (formation of third aggregates).
[0213] The resulting liquid dispersion of third aggregates is
heated to make the aggregates fuse and coalesce together and form
toner particles (fusion and coalescence).
[0214] The following describes this process in detail.
[0215] It should be noted that the process described below gives
toner particles that contain a coloring agent and a release agent,
but the use of coloring and release agents is optional. Naturally,
other additives may also be used. Preparation of Liquid Dispersions
of Resin Particles
[0216] First, liquid dispersions of resin particles, in each of
which particles of a binder resin have been dispersed (a liquid
dispersion of amorphous-resin particles and a liquid dispersion of
crystalline-resin particles), are prepared. A liquid dispersion of
coloring-agent particles and a liquid dispersion of release-agent
particles, for example, are also prepared.
[0217] The preparation of each liquid dispersion of resin particles
can be by, for example, producing it by dispersing the resin
particles in a dispersion medium using a surfactant.
[0218] An example of a dispersion medium for the liquid dispersions
of resin particles is an aqueous medium.
[0219] Examples of aqueous media include types of water, such as
distilled water and deionized water, and alcohols. One such
dispersion medium may be used alone, or two or more may be used in
combination.
[0220] Examples of surfactants include anionic surfactants, such as
sulfates, sulfonates, phosphates, and soap surfactants; cationic
surfactants, such as amine salts and quaternary ammonium salts; and
nonionic surfactants, such as polyethylene glycol surfactants,
ethylene oxide adducts of alkylphenols, and polyhydric alcohols. In
particular, anionic surfactants and cationic surfactants are
typical examples. A combination of a nonionic surfactant with an
anionic or cationic surfactant may also be used.
[0221] One surfactant may be used alone, or two or more may be used
in combination.
[0222] In the production of the liquid dispersions of resin
particles, the dispersion of the resin particles in the dispersion
medium can be by a commonly used dispersion technique, such as the
use of a rotary-shear homogenizer or a ball mill, sand mill,
Dyno-Mill, or other medium mill. For certain types of resin
particles, phase inversion emulsification, for instance, may
work.
[0223] In phase inversion emulsification, the resin to be dispersed
is first dissolved in a hydrophobic organic solvent in which the
resin is soluble. The resulting organic continuous phase (O phase)
is neutralized with a base, and then an aqueous medium (W phase) is
added. This converts the resin emulsion from the W/O to O/W form
(so-called phase inversion) and creates a discontinuous phase of
the resin, thereby dispersing particles of the resin in the aqueous
medium.
[0224] The volume-average diameter of the resin particles to be
dispersed in each liquid dispersion may be, for example, 0.01 .mu.m
or more and 1 .mu.m or less, preferably 0.08 .mu.m or more and 0.8
.mu.m or less, more preferably 0.1 .mu.m or more and 0.6 .mu.m or
less.
[0225] The volume-average diameter of resin particles can be
measured as follows. That is, the size distribution of the
particles is measured using a laser-diffraction particle size
distribution analyzer (e.g., HORIBA LA-700). The measured
distribution is divided into segments by particle size (channels),
and the cumulative distribution of volume is plotted starting from
the smallest diameter. The particle diameter at which the
cumulative volume is 50% of the total volume of the particles is
the volume-average diameter D50v of the particles. For the other
liquid dispersions, too, the volume-average diameter of particles
therein can be measured in the same way.
[0226] The resin particle content of each liquid dispersion of
resin particles may be, for example, 5% by mass or more and 50% by
mass or less, preferably 10% by mass or more and 40% by mass or
less.
[0227] The liquid dispersion of coloring-agent particles and the
liquid dispersion of release-agent particles, for example, are also
produced in the same way as the liquid dispersions of resin
particles. That is, what is described about the volume-average
diameter of particles, dispersion medium, how to disperse the
particles, and the particle content in relation to the liquid
dispersions of resin particles also applies to the particles of a
coloring agent and the particles of a release agent in their
respective liquid dispersions.
Formation of First Aggregates
[0228] Then the liquid dispersion of amorphous-resin particles is
mixed with the liquid dispersion of coloring-agent particles and
the liquid dispersion of release-agent particles.
[0229] In the resulting mixture of liquid dispersions, the
particles of an amorphous resin, a coloring agent, and a release
agent are allowed to aggregate together. This process of
heteroaggregation is continued until aggregates including particles
of an amorphous resin, a coloring agent, and a release agent (first
aggregates) grow to a diameter close to the planned diameter of the
toner particles.
[0230] Specifically, for example, a flocculant is added to the
mixture of liquid dispersions, and the pH of the mixture is
adjusted to an acidic level (e.g., a pH of 2 or more and 5 or
less). A dispersion stabilizer may optionally be added. The mixture
of liquid dispersions is then heated to a temperature near the
glass transition temperature of the resin particles (specifically,
for example, a temperature higher than or equal to the glass
transition temperature the resin particles minus 30.degree. C. but
not higher than the glass transition temperature of the resin
particles minus 10.degree. C.) making the particles dispersed in
the mixture form aggregates (first aggregates).
[0231] In the formation of first aggregates, the addition of the
flocculant may be carried out, for example, at room temperature
(e.g., 25.degree. C.) with the mixture of liquid dispersions
stirred using a rotary-shear homogenizer. Then the pH of the
mixture is adjusted to an acidic level (e.g., a pH of 2 or more and
5 or less), optionally followed by the addition of a dispersion
stabilizer, and the mixture is heated as described above.
[0232] Examples of flocculants include surfactants that have the
opposite polarity to the dispersing surfactant that has been added
to the mixture of liquid dispersions, inorganic metal salts, and
metal complexes having a valency of 2 or more. Using a metal
complex may help improve charging characteristics because in that
case less surfactant is used.
[0233] Optionally, an additive that forms a complex or similar bond
with metal ions from the flocculant may be used. An example is a
chelating agent.
[0234] Examples of inorganic metal salts include metal salts such
as calcium chloride, calcium nitrate, barium chloride, magnesium
chloride, zinc chloride, aluminum chloride, and aluminum sulfate
and also include polymers of inorganic metal salts, such as
polyaluminum chloride, polyaluminum hydroxide, and calcium
polysulfide.
[0235] Using a magnesium salt may be an easy way to ensure that the
finished toner will contain the Mg element. Preferably, the
flocculant is magnesium chloride.
[0236] The chelating agent, if used, may be a water-soluble one.
Examples of chelating agents include oxycarboxylic acids, such as
tartaric acid, citric acid, and gluconic acid, iminodiacetic acid
(IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic
acid (EDTA).
[0237] The amount of chelating agent added may be, for example,
0.01 parts by mass or more and 5.0 parts by mass or less,
preferably 0.1 parts by mass or more and less than 3.0 parts by
mass, per 100 parts by mass of the particles of an amorphous
resin.
Formation of Second Aggregates
[0238] The resulting liquid dispersion of first aggregates is mixed
with the liquid dispersion of amorphous-resin particles and the
liquid dispersion of crystalline-resin particles. Alternatively,
the liquid dispersion of first aggregates may be mixed with a
mixture of the liquid dispersion of amorphous-resin particles and
the liquid dispersion of crystalline-resin particles.
[0239] In the resulting mixture, in which first aggregates have
been dispersed together with particles of amorphous and crystalline
resins, the particles of amorphous and crystalline resins are
allowed to aggregate on the surface of the first aggregates.
[0240] Specifically, for example, the liquid dispersion of first
aggregates in which first aggregates have grown to a certain
diameter is combined with the liquid dispersion of amorphous-resin
particles and the liquid dispersion of crystalline-resin particles.
The resulting mixture is heated at a temperature equal to or lower
than the glass transition temperature of the particles of an
amorphous resin.
[0241] This process of inducing aggregation is repeated twice or
more. The resulting aggregates are second aggregates. Formation of
Third Aggregates
[0242] The resulting liquid dispersion of second aggregates is
mixed with the liquid dispersion of amorphous-resin particles.
[0243] In the resulting mixture, in which second aggregates have
been dispersed together with particles of an amorphous resin, the
particles of an amorphous resin are allowed to aggregate on the
surface of the second aggregates.
[0244] Specifically, for example, the liquid dispersion of second
aggregates in which second aggregates have grown to a certain
diameter is combined with the liquid dispersion of amorphous-resin
particles. The resulting mixture is heated at a temperature equal
to or lower than the glass transition temperature of the particles
of an amorphous resin.
[0245] Then the pH of the liquid dispersion is adjusted to
terminate aggregation.
Fusion and Coalescence
[0246] The resulting liquid dispersion of third aggregates is
heated, for example to a temperature equal to or higher than the
glass transition temperature of the particles of an amorphous resin
(e.g., to at least 10.degree. C. to 30.degree. C. higher than the
glass transition temperature of the particles of an amorphous
resin). This causes the aggregates to fuse and coalesce together
and form toner particles.
[0247] After the heat-induced fusion and coalescence, the
aggregates may be, for example, cooled to 30.degree. C. at a rate
of 5.degree. C./min or more and 40.degree. C./min or less. Rapid
cooling after the second aggregation promotes surface shrinkage,
and therefore surface cracking, of the toner particles. It appears
that rapid cooling under the above conditions forces the toner
particles to crack in the direction from inside toward the
surface.
[0248] Then the aggregates are heated again at a rate of
0.1.degree. C./min or more and 2.degree. C./min or less and kept at
a temperature equal to or higher than the melting temperature of
the crystalline resin minus 5.degree. C. for at least 10 minutes.
Then the aggregates are cooled slowly, at a rate of 0.1.degree.
C./min or more and 1.degree. C./min or less. This causes domains of
the crystalline resin to grow along the cracks, from the inside to
the surface of the toner particles, ensuring that the toner
particles will have domains of a crystalline resin meeting the
aforementioned conditions.
[0249] In addition, heating the rapidly cooled aggregates to a
temperature equal to or higher than the melting temperature of the
release agent, for example, often causes domains of the release
agent to grow to near the surface of the toner particles. After
rapid cooling, therefore, the aggregates may be heated to a
temperature equal to or higher than the melting temperature of the
crystalline resin minus 5.degree. C. but not higher than the
melting temperature of the release agent.
[0250] In this way, the toner particles are obtained.
[0251] After the end of fusion and coalescence, the toner
particles, formed in a solution, are washed, separated from the
solution, and dried by known methods to give dry toner
particles.
[0252] The washing can be by sufficient replacement with deionized
water in view of chargeability. The separation from the solution
can be by any method, but techniques such as suction filtration and
pressure filtration may help increase productivity. The drying,
too, can be by any method, but techniques such as lyophilization,
flash drying, fluidized drying, and vibrating fluidized drying may
help increase productivity.
[0253] Then a toner according to this exemplary embodiment is
produced, for example by mixing the dry toner particles with added
external additives including particles of at least one compound
represented by formula (1) and particles of a metal salt of a fatty
acid, both as described above. The mixing can be through the use
of, for example, a V-blender, Henschel mixer, or Lodige mixer.
Optionally, coarse particles may be removed from the toner, for
example using a vibrating sieve or air-jet sieve.
Electrostatic Charge Image Developer
[0254] An electrostatic charge image developer according to an
exemplary embodiment contains at least a toner according to the
above exemplary embodiment.
[0255] The electrostatic charge image developer according to this
exemplary embodiment may be a one-component developer, which is
substantially a toner according to an exemplary embodiment, or may
be a two-component developer, which is a mixture of the toner and a
carrier.
[0256] The carrier can be of any known type. Examples include
coated carriers, formed by a magnetic powder as a core material and
a coating resin with which the surface of the core material is
coated; magnetic powder-dispersed carriers, formed by a matrix
resin and a magnetic powder dispersed or mixed therein; and
resin-impregnated carriers, formed by a porous magnetic powder and
resin spread inside the magnetic powder.
[0257] Particles of a magnetic powder-dispersed or
resin-impregnated carrier may serve as a core material; these types
of carriers may be used with a resin coating thereon.
[0258] Examples of magnetic powders include a powder of a magnetic
metal, such as iron, nickel, or cobalt, and a powder of a magnetic
oxide, such as ferrite or magnetite.
[0259] Examples of resins, for use as a coating or matrix, include
polyethylene, polypropylene, polystyrene, polyvinyl acetate,
polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl
ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymers,
styrene-acrylate copolymers, straight silicone resins, which have
organosiloxane bonds, and their modified forms, fluoropolymers,
polyester, polycarbonate, phenolic resins, and epoxy resins.
[0260] Resins containing additives, such as electrically conductive
particles, may also be used.
[0261] Examples of electrically conductive particles include
particles of gold, silver, copper, or some other metal, carbon
black, titanium oxide, zinc oxide, tin oxide, barium sulfate,
aluminum borate, and potassium titanate.
[0262] The coating of the surface of the core material with a
coating resin can be by, for example, dissolving the coating resin
in a solvent, optionally with additives, and form a coating layer
with the resulting solution (solution for forming a coating layer).
The solvent can be of any kind and is selected considering, for
example, the coating resin used and suitability for coating.
[0263] Specific examples of techniques that can be used for this
resin coating include dipping, i.e., immersing the core material in
the solution for forming a coating layer; spraying, i.e., applying
a mist of the solution for forming a coating layer onto the surface
of the core material; fluidized bed coating, i.e., applying a mist
of the solution for forming a coating layer with the core material
floated on a stream of air; and kneader-coater coating, i.e.,
mixing the core material for the carrier and the solution for
forming a coating layer in a kneader-coater and then removing the
solvent.
[0264] In the case of a two-component developer, the mix ratio (by
mass) between the toner and the carrier may be between 1:100
(toner:carrier) and 30:100, preferably between 3:100 and
20:100.
Image Forming Apparatus/Image Forming Method
[0265] The following describes an image forming apparatus/image
forming method according to an exemplary embodiment.
[0266] An image forming apparatus according to this exemplary
embodiment includes an image carrier; a charging component that
charges the surface of the image carrier; an electrostatic charge
image creating component that creates an electrostatic charge image
on the charged surface of the image carrier; a developing component
that contains an electrostatic charge image developer and develops,
using the electrostatic charge image developer, the electrostatic
charge image on the surface of the image carrier to form a toner
image; a transfer component that transfers the toner image on the
surface of the image carrier to the surface of a recording medium;
and a fixing component that fixes the toner image on the surface of
the recording medium. The electrostatic charge image developer is
an electrostatic charge developer according to the above exemplary
embodiment.
[0267] The image forming apparatus according to this exemplary
embodiment performs an image forming method (image forming method
according to an exemplary embodiment) that includes charging the
surface of an image carrier; creating an electrostatic charge image
on the charged surface of the image carrier; developing, using an
electrostatic charge image developer according to the above
exemplary embodiment, the electrostatic charge image on the surface
of the image carrier to form a toner image; transferring the toner
image on the surface of the image carrier to the surface of a
recording medium; and fixing the toner image on the surface of the
recording medium.
[0268] The configuration of the image forming apparatus according
to this exemplary embodiment can be applied to well-known types of
image forming apparatuses, including direct-transfer apparatuses,
which transfer a toner image formed on the surface of an image
carrier directly to a recording medium; intermediate-transfer
apparatuses, which transfer a toner image formed on the surface of
an image carrier to the surface of an intermediate transfer body
(first transfer) and then transfer the toner image on the surface
of the intermediate transfer body to the surface of a recording
medium (second transfer); apparatuses having a cleaning component
that cleans the surface of the image carrier between the transfer
of the toner image and charging; and apparatuses having a static
eliminator that removes static electricity from the surface of the
image carrier by irradiating the surface with antistatic light
between the transfer of the toner image and charging.
[0269] Image forming apparatuses having a cleaning component that
cleans the surface of the image carrier may be particularly
suitable. An example of a cleaning component is a cleaning
blade.
[0270] The transfer component of an intermediate-transfer apparatus
may have, for example, an intermediate transfer body, a first
transfer component, and a second transfer component. The toner
image formed on the surface of the image carrier is transferred to
the surface of the intermediate transfer body by the first transfer
component (first transfer), and then the toner image on the surface
of the intermediate transfer body is transferred to the surface of
a recording medium by the second transfer component (second
transfer).
[0271] Part of the image forming apparatus according to this
exemplary embodiment, e.g., a portion including the developing
component, may have a cartridge structure, i.e., a structure that
allows the part to be detached from and attached again to the image
forming apparatus (or may be a process cartridge). An example of a
process cartridge is one that includes a developing component that
contains an electrostatic charge image developer according to the
above exemplary embodiment.
[0272] The following describes an example of an image forming
apparatus according to this exemplary embodiment. It is to be
understood that this example is not the only possible form of the
apparatus. The following describes some of its structural elements
with reference to a drawing.
[0273] FIG. 1 is a schematic view of the structure of an image
forming apparatus according to this exemplary embodiment.
[0274] The image forming apparatus illustrated in FIG. 1 includes
first to fourth electrophotographic image forming units 10Y, 10M,
10C, and 10K (image forming component) that produce images in the
colors of yellow (Y), magenta (M), cyan (C), and black (K),
respectively, based on color-separated image data. These image
forming units (hereinafter also referred to simply as "units") 10Y,
10M, 10C, and 10K are arranged in a horizontal row with a
predetermined distance therebetween. The units 10Y, 10M, 10C, and
10K may be process cartridges, i.e., units that can be detached
from and attached again to the image forming apparatus.
[0275] Above the units 10Y, 10M, 10C, and 10K in the drawing, an
intermediate transfer belt 20 as an intermediate transfer body
extends to pass through each of the units. There are a drive roller
22 (right in the drawing) and a support roller 24 (left in the
drawing) spaced apart from each other, and the intermediate
transfer belt 20 is wound over these two rollers, with the rollers
touching the inner surface of the intermediate transfer belt 20,
and is driven by them to run in the direction from the first unit
10Y to the fourth unit 10K. The support roller 24 is forced by a
spring or similar mechanism, not illustrated in the drawing, to go
away from the drive roller 22, thereby placing tension on the
intermediate transfer belt 20 wound over the two rollers. On the
image-carrying side of the intermediate transfer belt 20 is a
cleaning device 30 for the intermediate transfer belt 20 facing the
drive roller 22.
[0276] The units 10Y, 10M, 10C, and 10K, moreover, have developing
devices (developing component) 4Y, 4M, 4C, and 4K, to which toners
including those in the four colors of yellow, magenta, cyan, and
black, respectively, are delivered from toner cartridges 8Y, 8M,
8C, and 8K.
[0277] The first to fourth units 10Y, 10M, 10C, and 10K are
equivalent in structure. In the following, the first unit 10Y,
located upstream of the others in the direction of running of the
intermediate transfer belt 20 and forms a yellow image, is
described to represent the four units. The second to fourth units
10M, 10C, and 10K have structural elements equivalent to those of
the first unit 10Y, and these elements are designated with the same
numerals as in the first unit 10Y but with the letters M (for
magenta), C (for cyan), and K (for black), respectively, in place
of Y (for yellow).
[0278] The first unit 10Y has a photoreceptor 1Y that acts as an
image carrier. Around the photoreceptor 1Y are a charging roller
(example of a charging component) 2Y that charges the surface of
the photoreceptor 1Y to a predetermined potential; an exposure
device (example of an electrostatic charge image creating
component) 3 that irradiates the charged surface with a laser beam
3Y produced on the basis of a color-separated image signal to
create an electrostatic charge image there; a developing device
(example of a developing component) 4Y that supplies charged toner
to the electrostatic charge image to develop the electrostatic
charge image; a first transfer roller (example of a first transfer
component) 5Y that transfers the developed toner image to the
intermediate transfer belt 20; and a photoreceptor cleaning device
(example of a cleaning component) 6Y that removes residual toner
off the surface of the photoreceptor 1Y after the first transfer,
arranged in this order.
[0279] The first transfer roller 5Y is inside the intermediate
transfer belt 20 and faces the photoreceptor 1Y. Each of the first
transfer rollers 5Y, 5M, 5C, and 5K, moreover, is connected to a
bias power supply (not illustrated) that applies a first transfer
bias to the roller. Each bias power supply is controlled by a
controller, not illustrated in the drawing, to change the magnitude
of the transfer bias it applies to the corresponding first transfer
roller.
[0280] The operation of forming a yellow image at the first unit
10Y may be as described below.
[0281] Before the operation, the charging roller 2Y first charges
the surface of the photoreceptor 1Y to a potential of -600 V to
-800 V.
[0282] The photoreceptor 1Y is a stack of an electrically
conductive substrate (e.g., having a volume resistivity at
20.degree. C. of 1.times.10.sup.-6 .OMEGA.cm or less) and a
photosensitive layer thereon. The photosensitive layer is of high
electrical resistance (has the typical resistance of resin) in its
normal state, but when it is irradiated with a laser beam 3Y, the
resistivity of the irradiated portion changes. Thus, a laser beam
3Y is emitted using the exposure device 3 onto the charged surface
of the photoreceptor 1Y in accordance with data for the yellow
image sent from a controller, not illustrated in the drawing. The
laser beam 3Y hits the photosensitive layer on the surface of the
photoreceptor 1Y, creating an electrostatic charge image as a
pattern for the yellow image on the surface of the photoreceptor
1Y.
[0283] The electrostatic charge image is an image created on the
surface of the photoreceptor 1Y by electrical charging and is a
so-called negative latent image that is created as a result of the
charge on the surface of the photoreceptor 1Y flowing away in the
irradiated portion of the photosensitive layer, in which the
resistivity decreases by exposure to the laser beam 3Y, and staying
in the portion of the photosensitive layer not irradiated with the
laser beam 3Y.
[0284] As the photoreceptor 1Y rotates, the electrostatic charge
image created on the photoreceptor 1Y is moved to a predetermined
development point. At this development point, the electrostatic
charge image on the photoreceptor 1Y is visualized (developed) by
the developing device 4Y into a toner image.
[0285] Inside the developing device 4Y is an electrostatic charge
image developer that contains, for example, at least yellow toner
and a carrier. The yellow toner is on a developer roller (example
of a developer carrier) and has been triboelectrically charged with
the same polarity as the charge on the photoreceptor 1Y (negative)
as a result of being stirred inside the developing device 4Y. As
the surface of the photoreceptor 1Y passes through the developing
device 4Y, the yellow toner electrostatically adheres to the
uncharged, latent-image portion of the surface of the photoreceptor
1Y and develops the latent image. The photoreceptor 1Y, now having
a yellow toner image thereon, then continues rotating at a
predetermined speed, transporting the toner image developed thereon
to a predetermined first transfer point.
[0286] After the arrival of the yellow toner image on the
photoreceptor 1Y at the first transfer point, a first transfer bias
is applied to the first transfer roller 5Y. An electrostatic force
acts on the toner image in the direction from the photoreceptor 1Y
toward the first transfer roller 5Y, causing the toner image to be
transferred from the photoreceptor 1Y to the intermediate transfer
belt 20. The transfer bias applied here has the (+) polarity,
opposite the polarity of the toner (-), and its amount is
controlled by a controller (not illustrated). At the first unit
10Y, for example, it is controlled to +10 .mu.A.
[0287] Residual toner on the photoreceptor 1Y is removed and
collected at the photoreceptor cleaning device 6Y.
[0288] The first transfer biases applied to the first transfer
rollers 5M, 5C, and 5K of the second, third, and fourth units 10M,
10C, and 10K are also controlled in the same way as that at the
first unit 10Y.
[0289] The intermediate transfer belt 20 to which a yellow toner
image has been transferred at the first unit 10Y as described above
is then moved to pass through the second to fourth units 10M, 10C,
and 10K sequentially. Toner images in the respective colors are
overlaid, completing multilayer transfer.
[0290] The intermediate transfer belt 20 that has passed through
the first to fourth units and thereby completed multilayer transfer
of toner images in four colors then reaches the second transfer
section. The second transfer section is formed by the intermediate
transfer belt 20, the support roller 24, which touches the inner
surface of the intermediate transfer belt 20, and a second transfer
roller (example of a second transfer component) 26, which is on the
image-carrying side of the intermediate transfer belt 20. Recording
paper (example of a recording medium) P is fed to the point of
contact between the second transfer roller 26 and the intermediate
transfer belt 20 in a timed manner by a feeding mechanism, and a
second transfer bias is applied to the support roller 24. The
transfer bias applied here has the (-) polarity, the same as the
polarity of the toner (-).
[0291] An electrostatic force acts on the toner image in the
direction from the intermediate transfer belt 20 toward the
recording paper P, causing the toner image to be transferred from
the intermediate transfer belt 20 to the recording paper P. The
amount of the second transfer bias has been controlled and is
determined in accordance with the resistance detected by a
resistance detector (not illustrated) that detects the electrical
resistance of the second transfer section.
[0292] After that, the recording paper P is sent to the point of
pressure contact (nip) between a pair of fixing rollers at a fixing
device (example of a fixing component) 28. The toner image is fixed
on the recording paper P there, giving a fixed image.
[0293] The recording paper P to which the toner image is
transferred can be, for example, a piece of ordinary printing paper
for copiers, printers, etc., of electrophotographic type. In
addition to recording paper P, recording media such as
overhead-projector (OHP) sheets may also be used.
[0294] The use of recording paper P having a smooth surface may
help further improve the smoothness of the surface of the fixed
image. For example, the recording paper P may be coated paper,
which is paper with a coating, for example of resin, on its
surface, or art paper for printing.
[0295] The recording paper P to which a color image has been fixed
is transported to an ejection section to finish the formation of a
color image.
Process Cartridge/Toner Cartridge
[0296] The following describes a process cartridge according to an
exemplary embodiment.
[0297] A process cartridge according to this exemplary embodiment
includes a developing component that contains an electrostatic
charge image developer according to an above exemplary embodiment
and develops, using the electrostatic charge image developer, an
electrostatic charge image created on the surface of an image
carrier to form a toner image. The process cartridge can be
attached to and detached from an image forming apparatus.
[0298] The foregoing is not the only possible configuration of a
process cartridge according to this exemplary embodiment. Besides
the developing component, the process cartridge may optionally have
at least one extra component selected from an image carrier, a
charging component, an electrostatic charge image creating
component, a transfer component, etc.
[0299] The following describes an example of a process cartridge
according to this exemplary embodiment. It is to be understood that
this example is not the only possible form of the process
cartridge. The following describes some of its structural elements
with reference to a drawing.
[0300] FIG. 2 is a schematic view of the structure of a process
cartridge according to this exemplary embodiment.
[0301] The process cartridge 200 illustrated in FIG. 2 is a
cartridge formed by, for example, a housing 117 and components held
together therein. The housing 117 has attachment rails 116 and an
opening 118 for exposure to light. The components inside the
housing 117 include a photoreceptor 107 (example of an image
carrier) and a charging roller 108 (example of a charging
component), a developing device 111 (example of a developing
component), and a photoreceptor cleaning device 113 (example of a
cleaning component) provided around the photoreceptor 107.
[0302] FIG. 2 also illustrates an exposure device (example of an
electrostatic charge image creating component) 109, a transfer
device (example of a transfer component) 112, a fixing device
(example of a fixing component) 115, and recording paper (example
of a recording medium) 300.
[0303] The following describes a toner cartridge according to an
exemplary embodiment.
[0304] A toner cartridge according to this exemplary embodiment
contains a toner according to an above exemplary embodiment and can
be attached to and detached from an image forming apparatus. A
toner cartridge is a cartridge that stores replenishment toner for
a developing component placed inside an image forming
apparatus.
[0305] The image forming apparatus illustrated in FIG. 1 has been
configured so that toner cartridges 8Y, 8M, 8C, and 8K can be
detached from and attached again to it. The developing devices 4Y,
4M, 4C, and 4K are connected to their corresponding toner
cartridges (or the toner cartridges for their respective colors) by
toner feed tubing, not illustrated in the drawing. When there is
little toner in a toner cartridge, this toner cartridge is
replaced.
EXAMPLES
[0306] The following describes the above exemplary embodiments in
more specific terms, in further detail, by providing examples and
comparative examples. The above exemplary embodiments, however, are
by no means limited to these Examples. "Parts" and "%" used to
describe the quantity of something are by mass unless stated
otherwise. Production of Calcium Titanate Particles 1
(CaTiO.sub.3-1) Preparation of a Liquid Dispersion of Metatitanic
Acid
[0307] A liquid dispersion of metatitanic acid is desulfurized by
adjusting its pH to 9.0 with a 4.0 moles/liter aqueous solution of
sodium hydroxide, and the desulfurized dispersion is neutralized to
a pH of 5.5 with a 6.0 moles/liter hydrochloric acid. The
neutralized liquid dispersion of metatitanic acid is filtered, the
residue is washed with water, and water is added to the washed cake
of metatitanic acid to give a liquid dispersion containing the
equivalent of 1.25 moles of titanium oxide, TiO.sub.2, per liter.
The pH of this liquid dispersion is adjusted to 1.2 with a 6.0
moles/liter hydrochloric acid. The aggregates of metatitanic acid
in the liquid dispersion are deflocculated by stirring the
dispersion at a controlled temperature of 35.degree. C. for 1
hour.
Reaction of Calcium Titanate Particles 1
[0308] From the deflocculated dispersion of metatitanic acid, an
amount of metatitanic acid equivalent to 0.156 moles of titanium
oxide, TiO.sub.2, is sampled into a reactor. An aqueous solution of
calcium carbonate, CaCO.sub.3, is then added to the reactor. The
final concentration of titanium oxide in the reaction system is
0.156 moles/liter, and the calcium carbonate, CaCO.sub.3, is added
to make the molar ratio of calcium carbonate to titanium oxide 1.15
(CaCO.sub.3/TiO.sub.2=1.15/1.00).
[0309] The reactor is left for 20 minutes with a stream of nitrogen
thereinto so that its inside is purged with nitrogen. Then the
mixture inside the reactor, containing metatitanic acid and calcium
carbonate, is warmed to 90.degree. C. The pH is adjusted to 8.0
with an aqueous solution of sodium hydroxide over 14 hours, and the
mixture is stirred for 1 hour at 90.degree. C. to complete the
reaction.
[0310] The inside of the reactor in which the reaction has ended is
cooled to 40.degree. C., and the supernatant is removed in a
nitrogen atmosphere. The reactor is then decanted with 2,500 g of
purified water twice. After the decantation, the reaction system is
filtered using a Buchner funnel. The resulting cake is dried in the
air for 8 hours at an elevated temperature of 110.degree. C.
[0311] The resulting dry calcium titanate is put into an alumina
crucible and dehydrated and fired at 930.degree. C. The fired
calcium titanate is put into water and wet-ground using a sand
grinder to give a liquid dispersion. Excessive calcium carbonate is
removed by adjusting the pH to 2.0 with a 6.0 moles/liter
hydrochloric acid.
Surface-Modification of Calcium Titanate Particles 1
[0312] After the removal of excessive calcium carbonate, calcium
titanate surfaces are modified under wet conditions using SM7036EX
silicone oil emulsion (dimethylpolysiloxane emulsion) (Dow Corning
Toray Silicone Co., Ltd.). One hundred parts by mass, on a solids
basis, of calcium titanate is stirred with 1.0 part by mass of the
silicone emulsion oil for 30 minutes.
[0313] The mixture containing the surface-modified titanate is
neutralized to a pH of 6.5 with a 4.0 moles/liter aqueous solution
of sodium hydroxide. The neutralized mixture is filtered, and the
residue is washed and dried at 150.degree. C. The dried residue is
milled using a mechanical mill for 60 minutes. The resulting
particles are calcium titanate particles 1.
Production of Calcium Titanate Particles 2 to 6 (CaTiO.sub.3-2 to
-6)
[0314] Sets of calcium titanate particles differing in diameter are
produced in the same way as calcium titanate particles 1.
Adjustments are made to the duration of the addition of an aqueous
solution of sodium hydroxide, the pH reached thereby, and the
temperature and duration of the stirring after that. The resulting
sets of particles are calcium titanate particles 2 to 6.
[0315] The diameter of the particles becomes smaller with shorter
duration of the addition of an aqueous solution of sodium
hydroxide, lower pH reached thereby, and lower temperature and
shorter duration of the stirring after that. The opposites result
in larger diameters of the particles.
Production of Strontium Titanate Particles 1 (SrTiO.sub.3-1)
[0316] Particles of strontium titanate are produced in the same way
as calcium titanate particles 1. The calcium carbonate is changed
to strontium chloride, and the strontium chloride, SrCl.sub.2, is
added to make the molar ratio of strontium chloride to titanium
oxide 1.1 (SrCl.sub.2/TiO.sub.2=1.10/1.00). The resulting particles
are strontium titanate particles 1.
Production of Barium Titanate Particles 1 (BaTiO.sub.3-1)
[0317] Particles of barium titanate are produced in the same way as
calcium titanate particles 1. The calcium carbonate is changed to
barium chloride, and the barium chloride, BaCl.sub.2, is added to
make the molar ratio of barium chloride to titanium oxide 1.1
(BaCl.sub.2/TiO.sub.2=1.10/1.00). The resulting particles are
barium titanate particles 1.
Production of Zinc Stearate Particles
[0318] Particles of a metal salt of a fatty acid (particles of zinc
stearate) are produced by classifying ADEKA Corporation's ZNS-S
(particle diameter, 6.7 .mu.m) using an elbow-jet classifier
(EJ-L-3 (LABO), Nittetsu Mining Co., Ltd.). Sets of particles
having a volume-average diameter of 3 .mu.m, 5 .mu.m, and 8 .mu.m
are used.
Production of Zinc Behenate Particles
[0319] Particles of zinc behenate having a volume-average diameter
of 5 .mu.m are produced by classifying Nitto Kasei Kogyo K.K.'s
ZS-7 zinc behenate (particle diameter, 15.4 .mu.m) using an
elbow-jet classifier (EJ-L-3 (LABO), Nittetsu Mining Co.,
Ltd.).
Production of Zinc Montanate Particles
[0320] Particles of zinc montanate having a volume-average diameter
of 5 .mu.m are produced by classifying Nitto Kasei Kogyo K.K.'s
ZS-8 zinc montanate (particle diameter, 14.4 .mu.m) using an
elbow-jet classifier (EJ-L-3 (LABO), Nittetsu Mining Co.,
Ltd.).
Production of a Liquid Dispersion of Amorphous-Resin Particles
Production of Liquid Dispersion (A1) of Amorphous-Polyester-Resin
Particles
[0321] Terephthalic acid: 70 parts [0322] Fumaric acid: 30 parts
[0323] Ethylene glycol: 41 parts [0324] 1,5-Pentanediol: 48
parts
[0325] A flask equipped with a stirrer, a nitrogen inlet tube, a
temperature sensor, and a rectifying column is charged with the
above materials. With a stream of nitrogen into the flask, the
temperature is increased to 220.degree. C. over 1 hour. Then 1 part
of titanium tetraethoxide is added to 100 parts of the above
materials. The temperature is increased to 240.degree. C. over 0.5
hours while the water produced is removed, and dehydration
condensation is continued for 1 hour at this temperature. Cooling
the reaction product gives an amorphous polyester resin having a
weight-average molecular weight of 96,000 and a glass transition
temperature of 61.degree. C.
[0326] Forty parts of ethyl acetate and 25 parts of 2-butanol are
mixed together in a container equipped with a temperature
controller and a nitrogen purging system. One hundred parts of the
amorphous polyester resin is dissolved in the solvent mixture by
adding the resin little by little. The resulting solution is
stirred with a 10% aqueous solution of ammonia (amount equivalent
to three times, by molar ratio, the acid value of the resin) for 30
minutes. After the container is purged with dry nitrogen, the resin
is emulsified by adding 400 parts of deionized water at a rate of 2
parts/min with stirring at a constant temperature of 40.degree. C.
Returning the resulting emulsion to 25.degree. C. gives a liquid
dispersion of resin particles having a volume-average diameter of
190 nm. The solids content of this liquid dispersion of resin
particles is adjusted to 20% with deionized water. The resulting
dispersion is liquid dispersion (A1) of amorphous-polyester-resin
particles.
Production of a Liquid Dispersion of Crystalline-Polyester-Resin
Particles
Production of Liquid Dispersion (B2) of Crystalline-Polyester-Resin
Particles
[0327] 1,10-Decanedicarboxylic acid: 265 parts [0328]
1,6-Hexanediol: 168 parts [0329] Dibutyltin oxide (catalyst): 0.4
parts
[0330] The above ingredients are put into a three-neck flask dried
by heating. After the atmosphere inside the flask is made inert by
depressurization and nitrogen purging, the ingredients are
mechanically stirred with reflux at 180.degree. C. for 5 hours.
Then the mixture is heated gently to 230.degree. C. and stirred for
2 hours under reduced pressure. When the mixture becomes viscous,
the reaction is terminated by air-cooling. The resulting
crystalline polyester resin has a weight-average molecular weight
(Mw) (polystyrene-equivalent) of 13,000 and a melting temperature
of 69.degree. C. A mixture of 90 parts of the resin, 1.5 parts of
Neogen RK ionic surfactant (DKS Co., Ltd.), and 200 parts of
deionized water is heated to 120.degree. C., the resin is
thoroughly dispersed using IKA's ULTRA-TURRAX T50, and then the
resin is further dispersed for 1 hour using a pressure-pump Gaulin
homogenizer. The resulting dispersion is liquid dispersion (B2) of
crystalline-polyester-resin particles. The volume-average diameter
of the particles is 210 nm, and the solids content is 23 parts by
mass.
Preparation of a Liquid Dispersion of Coloring-Agent Particles
[0331] Carbon black (Regal 330, Cabot): 50 parts [0332] An anionic
surfactant (Neogen RK, DKS Co., Ltd.): 5 parts [0333] Deionized
water: 193 parts
[0334] A liquid dispersion of coloring-agent particles (solids
concentration, 20%) is prepared by mixing the above ingredients
together and processing the mixture for 10 minutes at 240 MPa using
an Ultimaizer (Sugino Machine). Preparation of Liquid Dispersions
of Release-Agent Particles Preparation of Liquid Dispersion (W1) of
Release-Agent Particles [0335] An ester wax (WEP-5, NOF
Corporation; melting temperature, 85.degree. C.): 100 parts [0336]
An anionic surfactant (Neogen RK, DKS Co., Ltd.): 1 part [0337]
Deionized water: 350 parts
[0338] The above materials are mixed together, and the mixture is
heated to 100.degree. C. The wax is dispersed using a homogenizer
(ULTRA-TURRAX T50, IKA) and then further dispersed using a
Manton-Gaulin high-pressure homogenizer (Gaulin). This gives a
liquid dispersion of release-agent particles (solids content, 20%).
The volume-average diameter of the particles is 220 nm.
Preparation of Liquid Dispersion (W2) of Release-Agent
Particles
[0339] A paraffin wax (HNP-0190, Nippon Seiro Co., Ltd; melting
temperature, 89.degree. C.): 100 parts [0340] An anionic surfactant
(Neogen RK, DKS Co., Ltd.): 1 part [0341] Deionized water: 350
parts
[0342] The above materials are mixed together, and the mixture is
heated to 100.degree. C. The wax is dispersed using a homogenizer
(ULTRA-TURRAX T50, IKA) and then further dispersed using a
Manton-Gaulin high-pressure homogenizer (Gaulin). This gives a
liquid dispersion of release-agent particles (solids content, 20%).
The volume-average diameter of the particles is 220 nm.
Example 1
Production of Toner Particles 1
[0343] Deionized water: 200 parts [0344] Liquid dispersion (A1) of
amorphous-polyester-resin particles: 200 parts [0345] Liquid
dispersion (W1) of release-agent particles: 10 parts [0346] The
liquid dispersion of coloring-agent particles: 20 parts [0347] An
anionic surfactant (Neogen RK, DKS Co., Ltd.; 20%): 2.8 parts
[0348] The above ingredients are put into a reactor equipped with a
thermometer, a pH meter, and a stirrer and are stirred for 30
minutes at a constant rate of 150 rpm and a constant temperature of
30.degree. C. while the temperature is controlled from the outside
using a mantle heater. Then the pH is adjusted to 3.0 with a 0.3 N
(=0.3 mol/L) nitric acid in preparation for aggregation.
[0349] The particles are dispersed using a homogenizer
(ULTRA-TURRAX T50, IKA), and at the same time an aqueous solution
of 0.7 parts of polyaluminum chloride (PAC, Oji Paper Co., Ltd.;
30% powder) in 7 parts of deionized water is added. The temperature
is increased to 44.degree. C. with stirring, and the diameter of
the particles is measured using Coulter Multisizer II (aperture
size, 50 .mu.m; Coulter) to ensure that the volume-average diameter
of the particles is 3.5 .mu.m. Then a mixture of 30 parts of liquid
dispersion (A1) of amorphous-polyester-resin particles and 15 parts
of liquid dispersion (B1) of crystalline-polyester-resin particles
is added. Thirty minutes later, a mixture of 30 parts of liquid
dispersion (A1) of amorphous-polyester-resin particles and 15 parts
of liquid dispersion (B1) of crystalline-polyester-resin particles
is added once again.
[0350] This addition of extra dispersions is repeated a total of
four times. That is, a mixture of 30 parts of liquid dispersion
(A1) of amorphous-polyester-resin particles and 15 parts of liquid
dispersion (B1) of crystalline-polyester-resin particles is added
four times.
[0351] Lastly, 47 parts of liquid dispersion (A1) of
amorphous-polyester-resin particles is added to make particles of
an amorphous polyester resin adhere to the surface of
aggregates.
[0352] Then 20 parts of a 10% aqueous solution of a NTA
(nitrilotriacetic acid) metal salt (CHELEST 70, Chelest
Corporation) is added, and the pH is brought to 9.0 with a 1 N (=1
mol/L) aqueous solution of sodium hydroxide. The resulting slurry
is heated to 90.degree. C. at a rate of 0.05.degree. C./min, kept
at 90.degree. C. for 3 hours, and then cooled to 30.degree. C. The
slurry is then heated at a rate of 0.05.degree. C./min to
87.degree. C., which is higher than the melting temperature of the
crystalline resin minus 5.degree. C., kept at this temperature for
30 minutes, cooled to 30.degree. C. slowly, at 0.5.degree. C./min,
and then filtered. The resulting crude toner particles are washed
by repeating dispersion in deionized water and filtration until the
electrical conductivity of the filtrate is 20 .mu.S/cm or less.
Separately, 8.5 parts of magnesium chloride, a source of the Mg
element, is dissolved in 80 parts of deionized water, and 20 parts
of sodium chloride is dissolved in 80 parts of deionized water. To
the crude toner particles washed and collected by filtration, 105
parts of the aqueous solution of magnesium chloride and 208 parts
of the aqueous solution of sodium chloride are added. Vacuum-drying
the resulting mixture in an oven at 40.degree. C. for 5 hours gives
toner particles having a volume-average diameter of 4.0 .mu.m
(toner particles 1).
Production of Toner 1
[0353] One hundred parts of toner particles 1 are mixed and blended
with the external additives specified in Table 1 and 1.5 parts by
mass of hydrophobic silica (RY50, Nippon Aerosil; number-average
particle diameter, 140 nm) at 10,000 rpm for 30 seconds using a
sample mill. The amounts of the external additives are as given in
Table 1. The resulting mixture is sieved through a 45-.mu.m mesh
vibrating sieve to give toner (toner 1). Toner 1 has a
volume-average particle diameter of 4.0 .mu.m.
Production of a Carrier
[0354] Five hundred parts of spherical particles of magnetite
(volume-average diameter, 0.55 .mu.m) are thoroughly stirred in a
Henschel mixer, and 5.0 parts of a titanate coupling agent is
added. The materials are mixed by stirring for 30 minutes at an
elevated temperature of 100.degree. C., giving spherical particles
of magnetite coated with a titanate coupling agent.
[0355] Then 500 parts of the coated magnetite particles are put
into a four-neck flask and mixed, by stirring, with 6.25 parts of
phenol, 9.25 parts of 35% formalin, 6.25 parts of 25% ammonia
solution, and 425 parts of water. The materials are allowed to
react at 85.degree. C. for 120 minutes with stirring and then
cooled to 25.degree. C. The precipitate is washed with water by
adding 500 parts of water and removing the supernatant. The washed
precipitate is dried at 150.degree. C. or more and 180.degree. C.
or less under reduced pressure, giving a carrier having an average
particle diameter of 35 .mu.m.
Production of Electrostatic Charge Image Developer 1
[0356] The resulting carrier and toner 1 are put into a V-blender
in a ratio of 5:95 (toner:carrier; by mass) and stirred for 20
minutes. The resulting mixture is electrostatic charge image
developer 1. [0357] Measurement of the Net Intensity of the Peak
for the Mg Element in the Toner in an X-Ray Fluorescence
Analysis
[0358] To quantify magnesium, the toner is analyzed by x-ray
fluorescence as follows. Approximately 5 g of the toner (including
the external additives) is compressed using a compression molding
machine under a load of 10 t for 60 seconds to give a 50-mm
diameter and 2-mm thick disk 50 mm across and 2 mm thick. This
sample disk is qualitatively and quantitatively analyzed for
chemical elements therein under the conditions below using a
scanning x-ray fluorescence spectrometer (Rigaku ZSX Primus II). In
the resulting spectrum, the net intensity of the peak for the Mg
element (in kcps, kilo-counts per second) is determined. [0359]
Tube voltage: 40 kV [0360] Tube current: 70 mA [0361] Anticathode
material: Rhodium [0362] Duration of measurement: 15 minutes [0363]
Spot diameter: 10 mm
Testing for Density Unevenness and Voids in Images
[0364] A sample image including a 50 mm.times.420 mm vertical band
chart is produced on 10,000 sheets of A3 J paper (Fuji Xerox Co.,
Ltd.) over two days under 28.5.degree. C. and 85% RH conditions
using a modified version of DocuCentre Color 400 (Fuji Xerox Co.,
Ltd.). After producing 10,000 images, the modified printer is shut
down, placed under 48.degree. C. and 95% RH conditions, and left
for 48 hours. The printer is then placed under 28.5.degree. C. and
85% RH conditions and left for 17 hours for tempering. A sample
image including a 50 mm.times.420 mm vertical band chart is printed
on 7,000 sheets of A3 J paper (Fuji Xerox Co., Ltd.) within a day.
The image is checked once every 1,000 sheets.
Density Unevenness
[0365] Density unevenness is graded according to the following
criteria. Grades A to D indicate acceptable unevenness.
[0366] A: The image and non-image portions of the photoreceptor
look the same, and the images are of acceptable quality.
[0367] B: A minor difference in gloss is visible between the image
and non-image portions of the photoreceptor, but the images are of
acceptable quality.
[0368] C: A difference in gloss is visible between the image and
non-image portions of the photoreceptor, but the images are of
acceptable quality.
[0369] D: A difference in gloss is visible between the image and
non-image portions of the photoreceptor. The images have minor
voids but are of acceptable quality.
[0370] E: A clear difference in gloss is visible between the image
and non-image portions of the photoreceptor, and the images have
voids.
[0371] F: Voids are noticeable in the images.
Voids in the Image
[0372] The clogging of the trimmer (voids in the image) is graded
according to the following criteria. Grades A to C indicate
acceptable voids.
[0373] A: No irregularities or streaks corresponding to the
structure of the developer brush are visible on the sleeve, and the
images are of acceptable quality.
[0374] B: Minor irregularities corresponding to the structure of
the developer brush are visible on the sleeve, but the images are
of acceptable quality.
[0375] C: Streaks made by the developer brush are visible on the
sleeve, but the images are of acceptable quality.
[0376] D: Streaks made by the developer brush are noticeable on the
sleeve, and the images have voids. Characterization of the Toner
Particles
[0377] The following characteristics of the toner particles are
determined as stated earlier herein. [0378] The aspect ratio of
domains of the crystalline resin (Aspect ratio AR in the table)
[0379] The length of domains of the crystalline resin along their
major axis (Major-axis length L.sub.cry in the table) [0380] The
percentage of the length of domains of the crystalline resin along
their major axis (L.sub.cry in the table) to the longest diameter
of the toner particle [0381] The angle between a line extended from
the major axis of domains of the crystalline resin and the tangent
to the surface of the toner particle at the point of contact
between the extended line and the surface (Major axis-to-tangent
angle .theta..sub.A in the table) [0382] The angle between lines
extended from the major axis of two domains of the crystalline
resin (Angle between extended major axes .theta..sub.B in the
table) [0383] The shortest distance between domains of the release
agent in the toner particle and the surface (outer edge) of the
toner particle (Shortest distance between release-agent domains and
toner-particle surface in the table) [0384] The percentage of toner
particles meeting the following conditions (toner particles A) to
all toner particles (% by number)
[0385] Condition (A): Each domain of the crystalline resin has an
aspect ratio of 5 or more and 40 or less.
[0386] Condition (B1): Each domain of the crystalline resin
measures 0.5 .mu.m or more and 1.5 .mu.m or less along its major
axis.
[0387] Condition (C): A line extended from the major axis of each
domain of the crystalline resin makes an angle of 60.degree. or
more and 90.degree. or less with the tangent to the surface of the
toner particle at the point of contact between the extended line
and the surface.
[0388] Condition (D): Lines extended from the major axis of the two
domains of the crystalline resin cross each other at an angle of
45.degree. or more and 90.degree. or less. [0389] The percentage of
toner particles meeting the following conditions (toner particles
B) to all toner particles (% by number)
[0390] Condition (A'): Each domain of the crystalline resin has an
aspect ratio of 10 or more and 40 or less.
[0391] Condition (B1'): Each domain of the crystalline resin
measures 0.8 .mu.m or more and 1.5 .mu.m or less along its major
axis.
[0392] Condition (C'): A line extended from the major axis of each
domain of the crystalline resin makes an angle of 75.degree. or
more and 90.degree. or less with the tangent to the surface of the
toner particle at the point of contact between the extended line
and the surface.
[0393] Condition (D'): Lines extended from the major axis of the
two domains of the crystalline resin cross each other at an angle
of 60.degree. or more and 90.degree. or less. [0394] The percentage
of toner particles meeting the following conditions (toner
particles C) to all toner particles (% by number)
[0395] Condition (A): Each domain of the crystalline resin has an
aspect ratio of 5 or more and 40 or less.
[0396] Condition (B2): Each domain of the crystalline resin
measures, along its major axis, 10% or more and 30% or less of the
longest diameter of the toner particle.
[0397] Condition (C): A line extended from the major axis of each
domain of the crystalline resin makes an angle of 60.degree. or
more and 90.degree. or less with the tangent to the surface of the
toner particle at the point of contact between the extended line
and the surface.
[0398] Condition (D): Lines extended from the major axis of the two
domains of the crystalline resin cross each other at an angle of
45.degree. or more and 90.degree. or less. [0399] The percentage of
toner particles meeting the following conditions (toner particles
D) to all toner particles (% by number)
[0400] Condition (A'): Each domain of the crystalline resin has an
aspect ratio of 10 or more and 40 or less.
[0401] Condition (B2'): Each domain of the crystalline resin
measures, along its major axis, 13% or more and 30% or less of the
longest diameter of the toner particle.
[0402] Condition (C'): A line extended from the major axis of each
domain of the crystalline resin makes an angle of 75.degree. or
more and 90.degree. or less with the tangent to the surface of the
toner particle at the point of contact between the extended line
and the surface.
[0403] Condition (D'): Lines extended from the major axis of the
two domains of the crystalline resin cross each other at an angle
of 60.degree. or more and 90.degree. or less.
Examples 2 to 19 and Comparative Examples 1 and 2
[0404] A toner and an electrostatic charge image developer are
produced and tested as in Example 1. The toner particles, the
particles of formula (1) and their quantity, and the metal salt
particles and their quantity are changed as indicated in Table 1.
The test results are presented in Table 1.
[0405] Toner particles 2 to 9 are produced as follows.
Production of Toner Particles 2
[0406] Toner particles are produced in the same way as toner
particles 1, except that the diameter of particles before the
addition of extra dispersions is changed to 4.1 .mu.m. This gives
toner particles having a volume-average diameter of 4.7 .mu.m
(toner particles 2).
Production of Toner Particles 3
[0407] Toner particles are produced in the same way as toner
particles 1, except that the diameter of particles before the
addition of extra dispersions is changed to 5.1 .mu.m. This gives
toner particles having a volume-average diameter of 5.8 .mu.m
(toner particles 3).
Production of Toner Particles 4
[0408] Toner particles are produced in the same way as toner
particles 1, except that the diameter of particles before the
addition of extra dispersions is changed to 6.4 .mu.m. This gives
toner particles having a volume-average diameter of 7.0 .mu.m
(toner particles 4).
Production of Toner Particles 5
[0409] Toner particles are produced in the same way as toner
particles 3, except that the amount of the magnesium chloride to
serve as a source of the Mg element is changed to 4.0 parts. The
resulting toner particles, having a volume-average diameter of 5.8
.mu.m, are toner particles 5.
Production of Toner Particles 6
[0410] Toner particles are produced in the same way as toner
particles 3, except that the amount of the magnesium chloride to
serve as a source of the Mg element is changed to 20 parts. The
resulting toner particles, having a volume-average diameter of 5.8
.mu.m, are toner particles 6.
Production of Toner Particles 7
[0411] Toner particles are produced in the same way as toner
particles 1, except that the amount of the magnesium chloride to
serve as a source of the Mg element is changed to 2.0 parts and
that the diameter of particles before the addition of extra
dispersions is changed to 3.0 .mu.m. This gives toner particles
having a volume-average diameter of 3.8 .mu.m (toner particles
7).
Production of Toner Particles 8
[0412] Toner particles are produced in the same way as toner
particles 1, except that the amount of the magnesium chloride to
serve as a source of the Mg element is changed to 30 parts and that
the diameter of particles before the addition of extra dispersions
is changed to 6.9 .mu.m. This gives toner particles having a
volume-average diameter of 7.5 .mu.m (toner particles 8).
Production of Toner Particles 9
[0413] Toner particles are produced in the same way as toner
particles 1, except that the diameter of particles before the
addition of extra dispersions is changed to 5.1 .mu.m and that the
rate of heating in the second round of heating, 0.05.degree.
C./min, is changed to 15.degree. C./min. The resulting toner
particles, having a volume-average diameter of 5.8 .mu.m, are toner
particles 9.
TABLE-US-00001 TABLE 1 Net intensity Particles of formula (1)
(kcps) of x-ray Toner particles Average Metal salt particles
fluorescence Volume- primary- Quantity Volume- Quantity Test
results from the Mg average particle (parts average (parts Density
Voids element in diameter diameter by diameter by uneven- in the
toner Type D (.mu.m) Type d1 (.mu.m) mass) D/d1 Type d2 (.mu.m)
mass) ness images Example 1 0.25 1 4.0 CaTiO.sub.3-1 0.1 0.2 40
ZnSt (C18) 3 0.20 A A Example 2 0.24 2 4.7 CaTiO.sub.3-1 0.1 0.2 47
ZnSt (C18) 3 0.20 A A Example 3 0.26 3 5.8 CaTiO.sub.3-1 0.1 0.2 58
ZnSt (C18) 3 0.20 A A Example 4 0.25 4 7.0 CaTiO.sub.3-1 0.1 0.2 70
ZnSt (C18) 3 0.20 A A Example 5 0.26 3 5.8 CaTiO.sub.3-2 0.05 0.2
116 ZnSt (C18) 3 0.20 A A Example 6 0.26 3 5.8 CaTiO.sub.3-3 0.15
0.2 39 ZnSt (C18) 3 0.20 A A Example 7 0.26 3 5.8 SrTiO.sub.3-1 0.1
0.2 58 ZnSt (C18) 3 0.20 A A Example 8 0.26 3 5.8 BaTiO.sub.3-1 0.1
0.2 58 ZnSt (C18) 3 0.20 A A Example 9 0.26 3 5.8 CaTiO.sub.3-1 0.1
0.2 58 ZnSt (C18) 3 0.20 A A Example 10 0.26 3 5.8 CaTiO.sub.3-1
0.1 0.2 58 ZnSt (C18) 3 0.20 A A Example 11 0.26 3 5.8
CaTiO.sub.3-4 0.4 0.2 15 ZnSt (C18) 3 0.20 A A Example 12 0.26 3
5.8 CaTiO.sub.3-1 0.1 0.2 58 ZnSt (C18) 3 0.20 A A Example 13 0.26
3 5.8 CaTiO.sub.3-1 0.1 0.2 58 ZnSt (C18) 5 0.20 A A Example 14
0.26 3 5.8 CaTiO.sub.3-1 0.1 0.2 58 ZnSt (C18) 8 0.20 C A Example
15 0.26 3 5.8 CaTiO.sub.3-1 0.1 0.2 58 Zinc 5 0.20 C B behenate
(C22) Example 16 0.26 3 5.8 CaTiO.sub.3-1 0.1 0.2 58 Zinc 5 0.20 C
B montanate (C28) Example 17 0.26 3 5.8 CaTiO.sub.3-5 0.03 0.2 193
ZnSt (C18) 3 0.20 D C Example 18 0.26 3 5.8 CaTiO.sub.3-6 5 0.2 1.2
ZnSt (C18) 3 0.20 C C Example 19 0.26 9 5.8 CaTiO.sub.3-1 0.1 0.2
58 ZnSt (C18) 3 0.20 B B Comparative 0.05 7 3.8 CaTiO.sub.3-1 0.1
0.02 38 ZnSt (C18) 3 0.20 E D Example 1 Comparative 1.4 8 7.5
CaTiO.sub.3-1 0.1 6 75 ZnSt (C18) 3 0.20 F D Example 2
[0414] Characteristics of toner particles 1 to 9 are presented in
Table 2.
TABLE-US-00002 TABLE 2 Domain A of the crystalline resin Percent-
age of the major-axis length to the Major Domain B of the
crystalline resin Toner particles Major- longest axis-to- Major-
Volume- Aspect axis diameter tangent Aspect axis average Mg ratio
length of the angle ratio length diameter content AR L.sub.cry
toner .theta..sub.A AR L.sub.cry Type D .mu.m kcps -- .mu.m
particle % Degrees -- .mu.m 1 4.0 0.25 22 1.1 28 84 21 1.1 2 4.7
0.24 23 1.2 26 81 20 1.1 3 5.8 0.26 24 1.2 21 79 21 1.0 4 7.0 0.25
20 1.1 16 80 19 1.0 5 5.8 0.1 21 1.3 22 83 20 1.2 6 5.8 1.2 24 1.2
21 81 22 1.1 7 3.8 0.05 22 1.2 32 83 22 1.0 8 7.5 1.4 23 1.2 16 84
23 1.1 9 5.8 0.26 3 0.2 5 53 2 0.3 Domain B of the crystalline
resin Percent- age of the Angle major-axis between length to
extended the Major major longest axis-to axes of Percentage of
toner particles diameter tangent domains meeting conditions (% by
number) Toner of the angle A and B Toner Toner Toner Toner
particles toner .theta..sub.A .theta..sub.B particles particles
particles particles Type particle % Degrees Degrees A B C D 1 28 81
76 94 78 92 77 2 23 80 81 93 77 91 77 3 17 78 77 92 80 91 80 4 14
79 78 91 78 91 77 5 21 81 79 93 78 93 76 6 19 80 78 94 79 92 78 7
26 79 75 92 78 91 77 8 15 78 77 93 77 90 76 9 4 39 51 0 0 0 0
[0415] The results indicate that the Examples may give images with
few voids compared with the Comparative Examples.
[0416] The foregoing description of the exemplary embodiments of
the present disclosure has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the disclosure to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the disclosure
and its practical applications, thereby enabling others skilled in
the art to understand the disclosure for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the disclosure be
defined by the following claims and their equivalents.
* * * * *